Confused

So  I was due for my period last Wednesday and it still hasn't come yet. I hadn't of had sex for 3 months and between then and now my periods have been very irregular. I've taken quite a few pregnancy tests and they've all been negative and  A week ago today I had unprotected sex. I'm not sure wether I could be pregnant and that's what's delayed it or it's because they're is something wrong. I really need everyone's help because I'm really unsure💕 I am not on any birth control either