Could I be pregnant?!

Okay so idk if this is the right group for my topic but me an my SO are trying to get pregnant.! We had unprotected sex the last day of my period which was Sunday an he came inside of me. An we had unprotected sex last night/this morning an he came inside of me, I'm due to ovulate in 3days. I been having really bad lower back pain, tiredness, sore nipples, headaches an nausea. Do you think I could be pregnant?! Do you think it's too early to take a test?! Please help all comments welcome.! 
I also read tho that it is possible to get pregnant when you have sex up to 5 days before you ovulate bcuz sperm can live up to 4-5days depending on the conditions of your vagina. So when you do ovulate there is sperm waiting for an egg to be released.! Is this true?!