I think that might be too much fiber your stomach could handle for now. Aside from oats, do have you eaten any food that might trigger stomachache as well?
Most times it feels numb when I sleep on one side. If you want to force yourself to sleep on your back, don't sleep with pillows on your head. It's easy to stay flat on your bed without the elevation on your head. It works for me even though it's uncomfortable.
It's a matter of lifestyle choice though. You can be a bachelor and be with any women you want for as long as you like. Settling for a monogamous relationship can provide you a chance of establishing a stable family.