Had sex using condom and withdrawal 1 week after start of last period. not on bc. now having lower stomach pressure period due in one week. pregnant?

Probably not: You will have to wait about 2 weeks to check a pregnancy test but if you have a normal period, the change of being pregnant is very low.

Likely not pregnant: More likely to be a urinary/bladder infection. Worth getting a urinalysis and getting antibiotics prescribed if you have a uti. Can check for pregnancy with store bought urine pregnancy test kit on or shortly after your due date.