I've never used AFF so the following are just my suggestions which have been pulled directly outta my ass
, but sanitized for your protection. (Heh, I get to use a new smilie...)
If this is really a concern for you I think you should list long/average or long/thick. If you really are over 7" long, then you are in the endowed minority, over the 5+"-6" average, or whatever the current statistics are. Girth, although discussed occasionally on this Board, does not seem to be a
common evaluation of erection size, although in my ignorance I might not be aware of the non-Board girth concerns. (And from the threads on this Board, there does seem to be a hankerin' for it.) Then, if AFF allows it, post your specific measurements in a free-text section where you can describe yourself and your Lil' Mikey.
And the 5 3/8" measurement? If you are truly that circumference, then just put 5 1/2". Unless you think you'll end up with the research scientist or statistician who really feels the need to check.
Good luck,
Thrax