Pregnancy Scare

I’m sophomore and only 15 years old. This guy, who is 17, and I had a thing for each other and we ended up having sex a little less than a month ago. We did use protection by the way, but my period is late. Today I had that brownish color stuff that happens right before your period or after, but it’s not as dark and it’s not heavy. I told my mom last night that my period was late and she was disappointed, but now this morning I could hardly get her to look at me. I brought it up and she kept asking me for exact dates so we could see when we would need to get a pregnancy test. I told her about the brownish stuff and she said well that can also be implantation bleeding. I started crying and that’s when my mom started actually acting like I was human being and that I was her daughter again. I made her promise not to tell anyone, including my dad or step dad because we don’t know if I am and there’s no reason for them to know right now. I’m scared to death and I don’t know what to do. I can’t sleep even though I feel tired, I can’t eat much even though I’m hungry, I don’t want to talk to people anymore like how I used to. Another thing I noticed is that there is also this white-ish clear-ish discharge in my underwear a little bit and when I wipe after I pee. I have had it before, but not for this long of a time. I don’t know what to do. I’m scared and I feel like I’m falling down into this deep black hole but when I get to the bottom I’m all alone and there’s no way for me to get out. Someone please help me.