What Causes Delayed Periods And Cramping After Taking Contraceptive Pills?

Hello!

I have a problem. I've had sexual intercourse about two months ago, right before I was about to get my period. I took emergency contraception just to be safe, and I've read that levonorgestrel can cause a heavy flow, but in my case I just had a light one. Now I haven't had my period for a month and a half. I took 3 pregnancy tests in different times of the month, and they all came out negative. In the last week I felt like I was gonna get my period every single day, cause I'm having cramps all the time, but I just never do. Could this be caused by emergency contraception or is something else going on in my body?

Thank you for your time and answer!