Took plan b still not getting period

Patient: Took a plan b then two weeks later boyfriend pre ejaculated in me. could i be pregnant i am 2 weeks late

Symptoms: Odd taste in my mouth, sudden hot flashes, fatigue, odd appetite, frequently urination. also, random sudden nausea but went away 3 mins after. took a plan be the 20th of july, started period a week later. going on three weeks now still no period. a week after i started bleeding from the second week of taking plan b. boyfriend pre ejaculated in me. goin on 2 weeks from when he did that. could i be pregnant. getting some symptoms. i have taken plan b a couple times with an ex i did not want to get pregnant with. and ive never had my period be this late. took three cheap $1 tests, and all came out negative. like four days ago. going to take clear blue test today. does anyone have any idea what could be going on.