He wants me to ride

okay so i love my boyfriend we've been together for almost 3 years. he makes me orgasm everytime, multiples sometimes. when we got together we did all kinds of crazy stuff(on random pieces of furniture etc) but lately we've gotten stuck in missionary (almost a year). we want to start mixing it up again. Anyway my real dilemma is that he's pretty well endowed and I can't take the whole thing when riding. me being overweight makes it harder to hold my self up higher resulting in giving up and going to missionary. I don't know what to do because doggy hurts too. by the way I'm trying to lose weight.