possible pregnancy symptoms?

Kirstyn
So I came off the pill nearly 4 weeks ago and af still hasn't come to visit! After the first week of no af, I took a pregnancy test and this was negative. Coming into nearly the 4th week I'm starting to feel tired all the time, my nipples are really sore, I've got lower back pain and my legs ache.
I don't know if I could be pregnant and should take another test asap or if my mind is just playing tricks on me! Did anybody else get similar symptoms?