Today is my 45th day of my cycle.. my last period date is nov 20. I had unprotected sex with my husband.. now-a-days I feel cramps at my bottom stomach.. I use HPT test on 39th day it shows negative result. Today early morning I check it with HPT test again it shows negative.. can anyone suggest am I pragnant or not? Shall I take blood test?

How old are you hon? If you are still young *under 21 or so* it is very common for your period to be very irregular. Some girls will skip a month or even 2!

Maybe you should see your doctor? Get a PG test with him/her, and start your yearly exams if you haven't yet (pelvic and pap)