I Had Sex A Month Ago. My Period Was Meant

I had sex a month ago. My period was meant to be 2-3 weeks after this time. I'm on day 46 of my cycle now which is unusual, I have irregular periods anyway, I had a hormone test which said my levels were normal. But I've noticed recently that my abdomen is bigger, I've done 2 pregnancy tests recently both negative. So I'm wondering why haven't I started my period, yes I have irregular periods but they are barely ever this long apart from the last cycle?