pregnant?

okay, so i got off of my period 8 days ago, and i have had unprotected sex once between them and now, but he pulled out. i am 15 so my periods could be irregular still. i started lightly bleeding today. and i have been a little bloated, head ache and cramping today so of course i looked this up on the internet (bad idea, freaked myself out) all of which those things are pregnancy symptoms. so i bought two 1st response pregnancy tests. and i've taken one, says i am not pregnant. i was planning on waiting to the the second one until next week just in case it's too early to tell i guess? i really cannot be pregnant right now. i guess i'm just asking for opinions, people with similar situations or stories. let me know! thanks!