What Are The Side Effects Of Depo Provera Injection?

i was on the depo birth control and only had the shot for a few months. ive been off of it for about 6 months now, and i had unprotected sex recently. i havent had my period within that 6 months and after i had sex i got it about 2 days later. its been almost two weeks now that ive had it. ive been really tired but other than that dont really feel pregnant. is there a chance that i could be?