Fat girlfriend; small penis

My penis is relativly small, right on 5.0" as a result anything other than missionary can be frustrating for me with a thin female.

But, with my 370 lbs girlfriend its impossible, I'm not sure it even works in missionary. It makes my frustrating situation more obvious.

I might have to break up with her. But she's my first girlfriend in 19 years so I dont really want to lose her.

Any ideas on how to bring up the subject of her losing weight?

5 inches with a thin female is more than enough.

And it's not the only way...

Have you thought of cowgirl position? Where she's on top? Have you done doggy-style?