chunky and insecure

So I've been with my now husband for 6 years. We haven't had sex in 2 years because I have gained weight after having our son. when we first met I was skinny and confident. He shows the want and affection however, I feel so uncomfortable like he will be disappointed once we get started. I avoid sex at all cost but I really want it. I want to have another baby and have a healthy sex life again. PLEASE GIVE ME ADVICE ON HOW TO FIX THIS. What can I do to feel comfortable? what can o try to spice up the bedroom? his birthday is Saturday AND I'm ovulating please help!!!!