Three weeks late, used a condom, but could I be pregnant?

So, the monthly's running a bit late. I completely missed last month, I was suppose to get it around the 12th of March, and now it's April 4th and I still haven't gotten it. My boyfriend and I both lost our virginity to each other and we used a condom and all and it didn't break or leak or slip off. And I'm pretty sure it was on correctly, at least it felt like it was. But anyhow, I noticed that I have been experiencing some of the pregnancy symptoms like cramping and discharge and such but it's just, I'm not sure if it's because I'm pregnant, or because it was my first time, or because I'm just overly paranoid about all of this. I took three home pregnancy tests and they all came up negative, but I know that they could be false negatives. I also have problems with my thyroid and actually had to have it removed last October so now I'm on thyroid hormone supplements and I missed a couple doses so I'm pretty sure that contributed to the lateness. But I was just wondering what you all think, like if you all think there could be a chance that I'm pregnant or if I'm just being paranoid?