Thanks for your thoughts, this was just for fun 
When I first started reading I thought [name_f]Louisa[/name_f] but after reading all of it, I think [name_f]Maren[/name_f] suits her just fine.
Plus, using [name_f]Maren[/name_f] would save her the explanation of “Oh, I go by middle name because…”
If she doesn’t like what you choose, she can always change what she wants to go by as she becomes more independent. Whether it be [name_f]Maren[/name_f], [name_f]Louisa[/name_f] or even [name_f]Lula[/name_f]
Honestly? It is way, way too late to change your daughter’s name.
From that description, I actually picture a [name_f]Maren[/name_f] more than a [name_f]Louisa[/name_f].
Keep it as [name_f]Lula[/name_f] since that’s what she’s called for the majority of the time, and tell relatives/friends/teachers that’s what she goes by.
I wouldn’t worry about her growing out of it. I know so many grown women with endearingly childish names who pull them off just fine - [name_f]Libby[/name_f], [name_f]Daisy[/name_f], [name_f]Liza[/name_f], [name_f]Katie[/name_f]. I even know a [name_f]Pixie[/name_f] who is a GP.
And there’s the old-Hollywood type trend of similar names too… [name_f]Tippi[/name_f], [name_f]Etta[/name_f], [name_f]Heidi[/name_f].
And if SHE really feels it necessary, she’s got both [name_f]Maren[/name_f] and [name_f]Louisa[/name_f] to fall back on in the future.
I am not looking to change it at all, I love her name! We have just been calling her by both of her names (not really intentionally, it just happened), and I would like to start calling her just by one name. Either way, she already knows the name, she responds to both her first name and middle name, as well as her nickname. If anything, I would like to use her nickname less and focus on what I would like her to be called long term, first or middle. I suppose we could wait until she is older and let her decide herself.
but [name_f]Maren[/name_f] is more common.
I like [name_f]Louisa[/name_f] and it sounds more like what she is being called now.
Tell her teachers she should be known as [name_f]Maren[/name_f]. It’s a lovely name.
Quick story: My dad’s name is [name_m]Richard[/name_m] [name_m]John[/name_m] and he goes by [name_m]John[/name_m]. It’s always been a pain for him. People always call him [name_m]Richard[/name_m] and he always gets mail addressed to [name_m]Richard[/name_m]. Calling her [name_f]Maren[/name_f] will save her a lot of headaches in the future.
By the way, I remember when you named her. Lots of Berries told you what a stunning name [name_f]Maren[/name_f] [name_f]Louisa[/name_f] is and they’re right!
[name_f]Maren[/name_f], definitely.
My husband has the same situation sarahmezz described. I always warn berries about purposefully planning on calling their child by their middle name. My husband hates it and it has caused a fair amount of logistical problems for him. And [name_f]Maren[/name_f] [name_f]Louisa[/name_f] is a fantastic name btw, stick with that.
Also, side note: I somehow developed the nickname Loubell as a young girl. I was called Loubell by family members for years, including variations like [name_u]Lou[/name_u], [name_f]Loulou[/name_f], [name_f]Belle[/name_f] and [name_u]Lou[/name_u] Bega, which eventually just turned into Bega… That was only one sister tho. The point is that I always went by my first name, but was just as often (if not more) called Loubell or some variation. I am still called that today by family members, just not nearly as much. If family members call your daughter [name_f]Lula[/name_f], great! She can be called both that and her given name. It’s fine! It will work out. I don’t think you have to be so finite in what you want to call her. That’s how great nicknames develop after all!!!
A perfect [name_f]Maren[/name_f] in my eyes. I think [name_f]Maren[/name_f]'s absolutely adorable.
[name_f]Maren[/name_f] and [name_f]Lula[/name_f] are both fantastic, original names. From your description, [name_f]Lula[/name_f] suits her best. Keep her name as it is: “My name is [name_f]Maren[/name_f] [name_f]Louisa[/name_f] - some people call me [name_f]Lula[/name_f]. I like to be called …”
Keep on using all three names as it seems right at the time. I feel that she will associate with [name_f]Lula[/name_f] the most especially since her sisters chose her pet name.
When she is older she will claim the name that she identifies the most with but that doesn’t mean that she can’t answer to three names that she is used to.
In my mother’s family she and her siblings had at least two nicknames and my mother for one has never answered to her [name_m]Christian[/name_m] name of [name_f]Margaret[/name_f] at all and neither was she called [name_f]Margaret[/name_f] by anyone it was always [name_f]Margot[/name_f] plus an extra two nicknames.
I too am known by my middle name and I love it and the few special people who call me by my first name are not random strangers (although I get this from telemarketers) but people who have known me all my life and have special license to call me by my first name.
I love my first name but I identify more with my middle.
So, just let time take over and I am sure that it will resolve itself naturally.
rollo
Thank you, everyone! You know what? Suddenly I don’t feel the urge to force it anymore.
I think we will just carry on and let the pieces fall where they may as she gets older. I haven’t been able to commit either way, because I adore both [name_f]Maren[/name_f] and [name_f]Louisa[/name_f]. But when I think about what name suits her best, I just think “she is a [name_f]Lula[/name_f]!” because that is what she is called most of the time (the pet name suits her perfectly for now).
I guess I have just been concerned that people may be confused or think that it is weird that her name is [name_f]Maren[/name_f] but her close loved ones call her [name_f]Lula[/name_f] ;). I hadn’t really considered her going by [name_f]Louisa[/name_f] until her nickname stuck and I started wondering if it would be a more intuitive transition to a full name when she gets a little older. It would be easier if I loved one name more than the other…[name_f]Louisa[/name_f] has been a long time favorite, but I love [name_f]Maren[/name_f] more and more every day.
I appreciate your replies, it gives me some perspective.
I think [name_f]Maren[/name_f] suits her best from your description. She sounds like she has a lot of spunk! 
[name_f]Maren[/name_f] [name_f]Louisa[/name_f] is gorgeous!