I never had a nickname, and it only bothered me in high school for a little while, not enough to force everyone to call me [name]Kari[/name], or however I meant to spell it. In reality, I guess I didn’t love or prefer the nickname over my name, it was more of a vanity. I thought it would seem cooler, but it really wasn’t me. I tend to like a lot of names with no nicknames.
I don’t really know why people are obsessed so much with “options.” I guess a lot of name enthusiasts think a lot about their own names and have their whole life as something they feel lucky to have or doesn’t fit them quite right, and admitting that we don’t know what our children will be like, we want to make sure they aren’t stuck to a name we like but they don’t. But yet, we love names and take a lot of time to pick them out, and along with that, nicknames we intend to use - so really, where is the option if you already set them up with the nickname? Where is your confidence that the name you choose is right? I think “options” is another way of saying either you’re not really sure, or in the case of name nerds, maybe settling on one name is easier when it easily fans out into 5 or 6 other names. I can appreciate how awesome a bargain that is, but as someone without any nicknames, I hardly think it’s a requirement.
I really don’t think [name]Erin[/name] needs a nickname. If you like [name]Erin[/name], names like [name]Erin[/name] tend to be lengthened rather than shortened, fairly informal and diminutive such as Er-[name]Bear[/name] (or anything that rhymes or makes an adorable phrase which will embarrass her before she’s 10yo), or just E. Hardly the sort of thing to go with [name]Maisie[/name] and [name]Dottie[/name] and [name]Libby[/name] that people are always talking about. I can think maybe [name]Erly[/name] (not pronounced like early, more like Airly), Erzy (Ersie? prn Airzee), or Rinzie. It’s kind of a stretch, but if you want something catchy and nicknamey like a lot of the other names, adding a -lee or -zee sound fits into the template without being too complicated or convoluted.
Repeating the consonant +ee of the first syllable is most common, but I don’t like Erry or [name]Eri[/name]. They look like “error,” sound like “airy” and don’t really set apart from the name [name]Erin[/name] enough to bother - to me, it’s not enough to have a nickname just for the sake of having it. [name]Erin[/name] isn’t too grown up for a child to handle or too childish for a grown-up to handle, which is another reason a lot of people like nicknames, but there’s really no reason to call her [name]Eri[/name] instead of [name]Erin[/name] intentionally. If it happens to catch on, well, what am I going to do. I’m not the name police. 