Top wise I use website called anything5pound.com and go to there plus size section and get tops in size 20 that are flowing and long seem to fit well for a pregnancy belly.
I am 34 weeks and still using my size 18 and 20 leggings but have also got over bump leggings from H&M there size XL fit well and are only £7.99
Asda jeans at size 20 under bump are to big for me but there size 20 over bump fit well seem very generous in size 20 at Asda.
I rang from size 16 in dresses to 20 in jeans I'm bottom heavy so looking around helps :) Hope that's some help expesh if you do not want to spend loads.