Haven't had sex for 2 years, but engaged.

Hi there,
Recently my boyfriend of five years popped the question! I was ecstatic to hear as he is everything to me and seriously the best guy I have ever met. The one problem, we don't have sex. Sure we will do some oral activities but never the real deal. To break it down, we are two plus size people that lost it to each other at 19 years old and although I am happy it was him. He is very body concious but also is very sexual in his own way. I feel like he may have performers fright, but it's been two long years and no one knows. Any advice?