Mind you I suppose you have given it a go, sleeping on your stomach is a bit of a problem.
Did you try any of the cloth masks, there is a nasal one and a full-faced one. In fact I think they have improved one out now, though whether they improved them or not is a matter of opinion.
A newer machine might be a bit better, but I would try one of the cloth masks if you havn't done so, they can be a bit difficult to get to seal at the start and do need to be cleaned a bit more and have a limited life, but if I were in your shoes I would give one a go.
CPAP is not easy for some people, I was lucky in that I made up my mind it had to work and I just started using it every night, even though I had problems at the start and had a big struggle with masks. There was no one to ask back then, I wish a place like this has existed so I could have asked other users for advice.
What have you tried? Is it just Nasal Pillows and a Full-faced mask?
Oh and welcome to the forum Cthom1
Every journey, however large or small starts with the first step.