17 and TTC

I'm 17, about to be 18 in May, my boyfriend is 18 about to be 19 in February. We both really want a baby. On the 7th we had sex with a condom, but the condom slipped off inside me, we think it's because he came twice in it but we had to reach really far up to get it... i know tmi but once we got it out there was no cum in it. We were flipping out about me getting pregnant, 2 weeks later I took a test and it came out negative, it was a relief because of how young I am and we don't know how we'll tell our parents but then again we both got really sad and depressed that it wasn't postive because we both do want a baby... so after that we decided to go ahead and start trying, I haven't started my period yet this month when it should of already going based off last month. But my period is very irregular and even skips months sometimes. He came in my atleast 8 times last week. Can anyone give me any advice or symptoms that you can tell maybe before I test again before his birthday or anything? Thank you