irregular period all my life, negative on pregnancy test

I've taken 4 home pregnancy tests and they have all came out negative. My boobs have been sore for 2 weeks now, and there is a lot of pressure on my whole stomach but mostly my lower abdomen. Its not just my lower back hurts but all over, I've been eating everything in sight and I have been feeling sick but not to the point to throw up. When I go pee its fine until im almost done its like I get a really bad cramp in my lower stomach. I have never had a regular cycle even when I was on birth control for 2 years. I get my period when it wants to come, and the last time I got my period was about 2 1/2 months ago. So does that mean that I wont be able to tale a pregnancy test until 2 months after im actually pregnant for it to show up at positive?

I have all the pregnancy symptoms just not the positive answer.
Can you please help me and give me some alternative factors this could be so I can stop freaking out.