I have the same problem but I just wear a CAMI under everything to try and make it work and so far it has!
Online is a lot better for unusual fits. I got a lot of maternity clothes on eBay. They measure the actual garment rather than just telling you a size, which is useful.
The maternity leggings and jeans from asda are actually really good, I'm 5'10 and a size 12 although I buy size 14 clothes for maternity wear just for added comfort. The tops out of mothercare are nice and long too x
Funny as it is if you are just at home
buy some guys t shirts and tear the collar of it off that will make the neck roll and it keeps it alilttle girly and you can buy cami's there always nice