Im 5'4 and size 24 to 26 i dont know what style of wedding dress to go for.im 44dd bust,have rounded shoulders?

I would like something that will look sexy and classy not like a tent,im getting married in a registry office so therefore i dont want a very wide dress.im not very good in high heels either so i cant use those to make me look taller and narrower and i dont want to look like a little dumpling !!!!!! my budget is quite limited about �100 to �700 max.i live in northamtonshire area can anyone help.PLEASE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!