hun ur fears are totally normal!
as for ur fundal height, if ur doc isnt trained in pregnancy care which by the sounds of things givin he couldnt pinpoint how high ur uterus was, he's not, then i wouldnt worry too much.
nd alot of things can affect fundal height! and if u dnt know exactly when ur last AF was then maybe u are a little bit behind in ur own dates too. best bet is to get a scan done!
let us know how u go
xxx