Low progesterone levels

Im a first time here. I've just found out my progesterone levels are 3.1. So I'm quite distressed about it because my partner and myself have been trying for 19 months now. I just tried to think it was nothing to worry about so months went on. I'm nearly 31, I had an abortion against my wishes 4 years ago, and I'm still struggling with that but the thought I cant conceive again is awful. What can I do to increase my progesterone levels? Apart from walnuts, yams, b12... Any advice would be amazing coz I'm desperate x