Confused, pregnant or not.

I'm 20 years old and I've been having a very regular period for quite some time now. The month of aug I had unprotected sex and he didn't get pulled out. So I took the plan b pill. I imediantly had my period a week later for the reguar 5 day cycle. I had sex again the beginning of September but he never finished. I missed my period in September and I'm about to miss mine in October in just a few days. I've been having alot of pregnancy like symptoms such as bloated, tired, fatigue, nausea, cramping, sore breasts, constant pressure in my stomach, higher temp, increases appetite, and weight gain. I overall feel extremely different and was for sure
I was pregnant. I took 3 HPT's and they were all negative. I don't understand why it wouldn't have shown up by now being 2 months late and 2 and a half since my last period. I recently started to have a sharp pain in the left side of my stomach diagonal from my belly button. It started out only every so often but has increased to everytime I sit up or strain my stomach. I'm planning on getting a test done at the health department on Monday. But I'm extremely confused. I just wana know at this point if Im not why havent my periods came? Could I still be pregnant with 3 neg HPT's after 8 weeks? Or what else could be wrong and causing the pain and missed period? ALSO, I have had NO bleeding whatsoever. Not even spotting.