sever pain is not "normal"..back pain can be..but severe back pain could be SIGNs of a problem. not aways....but you dont even know if your even pregnant so i wouldnt be worried about signs and stuff till you know iof your pregnant.
period pain....aka..cramps...is normal.
only a doctor can tell you if there is anything preventing you from getting pregnant.
if your having trouble getting pregnant, go to a fertility doctor. it might be something going on with your or maybe your husband has a low sperm count or something.