Late Period

Hey girls! My last period I got was the 9th of July and that was the first day of it. Then me and my boyfriend went camping, one thing led to another and we bought a plan b and i took that on the 19th of july. I haven’t gotten my period since and it’s the 21st of August. I’m worried and I’m not sure if it’s stress from going back to nursing school or just from the plan b. i’ve taken 2 pregnancy tests like 2 weeks ago and they were both negative. Could any of you guys give me some advice? i’m only 20 and he’s 24 and we’re responsible but don’t want a baby right now 😭😅