Uti or early pregnancy symptoms?

I think I'm about 8 dpo, I have not been keeping track lately, we only bd once during my fertile week. My af is due on the 20th. Two nights ago I have severe cramps in my lower abdominal and my lower back, it was so bad that yesterday it still didn't feel right and it was tender to touch, I still don't feel right, I am also peeing more often and my liquid intake has not increased. I've never had a uti before so I don't know what it feels like? Unrelated to a uti but my nipples are sore to touch. Thank you in advance!