I'm 15 and I'm worried that I might be pregnant?

Please help me, I can't tell my parents or talk to anyone else about this, so please take the time to read this post (I know it's long) it would really help with my situation! I had sex with my long term boyfriend two weeks ago, we were a bit worried so I went to the health nurse at school and got the ECP (I am 15, nearly 16 and my boyfriend and I are in a steady relationship, we don't have sex much at all, because if my parents would kill me if they knew). My period usually starts around the first of the month, last month it started on the 2nd, and finished on the 7th. The health nurse told me I wouldn't have been ovulating but she gave me the ECP anyway because I was worried. A week after that, on the Saturday my boyfriend and I had unprotected sex about 4 times, I realize this was stupid but I justified it with the fact that I wasn't close to ovulating - because I know I ovulate around a few days after my period ends. Around this time I have been under a lot of pressure from friends, parents and schoolwork, meaning I have been under an unusual amount of stress, which I don't cope well with. I am now around 2 days late for my period, which I usually would disregard, seeing as sometimes my period is a few days early or late, but now I am really starting to worry and I know that stress making periods late is very common, and I have had no other symptoms of pregnancy other than slight discharge of a slightly sticky jelly-like consistency which is usually what happens before my periods sometimes anyway. I know I sound paranoid and this is a really long question but I can't talk to anyone other than my boyfriend and the health nurse in two weeks about it, please help!