My bf has a small penis. He is overweight and his penis is hidden somewhat. The tip sticks out but if you move the flap of skin around the shaft you can see it's longer down there. Is there anything to fix that? How do we have sex?

I don't think it's that your boyfriend's penis is small. It's that your boyfriend's abdominal apron (that's the term for when the abdomen is so enlarged it hangs over the waist and overlaps the front of the belly) is covering up a portion of the shaft, obscuring some of the penis' length. You might want to choose a sexual position where his abdomen wouldn't be in the way, like if you were on top (when he lays on his back, the extra girth can distribute a little more evenly around his body). But if he's going to be on top of you, his abdomen will likely continue to get in the way.

How is your boyfriend's health overall? Obesity can come with a lot of health complications like poor cardiovascular condition and diabetes. Poor health related to obesity can have negative affects on sexual function ranging to depression due to poor body image, to erectile dysfunction to elevated risks of heart attacks during strenuous activity (i.e. vigorous sex). Has he seen a doctor for a checkup? How are his health habits? As his girlfriend, you can have some positive influence if you lead by example (just don't nag! people hate nagging nellies!). You can drink more water instead of soda, take him on walks or play sports together, and you can steer him towards healthier eating choices when you go out for meals (i.e., go to a salad bar instead of a steak house).