I use a 22 g and it's not bad at all.
Just buck up and do it and I promise you won't think it's as bad as you are building it up in your head! Do you have someone that can do it for you?
Keep thinking of the end result, focus on it!
Just think, it'll be nothing compared to child birth, getting an epidural and/or having a csection.
Seriously, just try it one time and if you really can't handle it then talk to your RE about another option.