Trying to get pregnant

So I have been trying to get pregnant for a while now, but it is very hard for me to track my periods. I haven’t gotten a period in a while due to me stopping birth control. My last period was on December 25 and lasted 7 days. I got my period due to a pill my obgyn suggested I take to make my period come. My app says I ovulated January 7. I had sex almost every other day that week. Starting last week, I’ve been very crampy on my lower left and right side. I have headaches, and also been nauseous. I normally have headaches almost every day, but these headaches are a lot more intense, and I feel very out of it and some what light headed. I have taken multiple test but they all say not pregnant. I’m not sure what to do.. at this point. I really want to be pregnant, but it is so hard for me.