Firstly congratulations!
Honestly naming is such a challenging thing to do we put so much pressure on ourselves to find the perfect name and it can be very overwhelming. I also think we put so much pressure on ourselves to nail the name before the baby comes when reality is babies don’t recognise their names until they are 6 months old so you have time to figure it all out. Try not to put so much pressure on yourself give yourself time to figure it all out.
Regarding name regret itself honestly I think this emotion is really normal. Having a baby is tough and with changes in hormones I think it does affect your ability to think straight/doubt your decisions. I felt name regret when I named my daughter [name_f]Lilia[/name_f] it’s really hard emotion how I tackled it was understanding why I love the name [name_f]Lilia[/name_f]. I created a pros and cons list surrounding the name (pros outweighed the cons), tried using the name surrounding her with conviction (I had a lot of people mispronounce her name which made me feel awkward so I learnt to correct with conviction) and I used nicknames which felt more accessible like Lils/lily. I also started falling back in love with [name_f]Lilia[/name_f] discovering why I loved her buying embroidered toys for her etc seeing the name in association made me love [name_f]Lilia[/name_f] more. I absolutely love [name_f]Lilia[/name_f] now and moved the past that period (the berries also massively helped) and I think potentially doing these things above would help you feel positive about your decision.
Concerning [name_f]Lucy[/name_f] herself she’s a Nameberry favourite for sure and I can see why she’s a classic choice with a bright feeling. [name_f]Lucy[/name_f] has a lovely meaning feels friendly and [name_f]Narnia[/name_f] is a cute association. I can totally see why you chose [name_f]Lucy[/name_f]!
Good luck