Ok I'm 18 and I'm worried that I might be pregnant I haven't been trying but my last period was june 16 lasted 4 days then june 22 I had unprotected sex and my boyfriend came inside me june 26 I sarted ovulating is there a chance I cud be pregnant I mean can sperm live up to 4 days?now its 5 days after ovulation started and I've been having horrible cramps and heartburn and constantly tired??cud these be symptoms of implantation taking place?please somebody help me!!