implantation bleeding?

Jessica
Ok, had unprotected sex with hubby the 3rd and 11th, but 11th was last day of period. Yesterday and today I have been spotting lightly and I don't start my period til next Sunday , June 4th. I took a test yesterday but it was negative. I was super nauseous this weekend as well. When I found out I was pregnant with my 1st I had implantation bleeding but I can't remember when since it was 4 years ago lol. Could I be pregnant?