Becca, unless you're planning on dating a 'man' half your age... they are used to seeing the 'girls' off to the side, lol. The only boobs that stay on top and don't move when you are on your back are the fakes
and even then it's because they are encapsulated (held there by scar tissue). Sorry to burst your bubble, but even building your pecs (which by the way are flattish
slabs of muscle) won't do all that much. Go on top, at least they will dangle tantalizingly within his reach, lol.