Uti or implant pains!

Ok- I've tested negative on day AF due- about 4 times... Lol- has anyone been confused between a uti and implantation? I am achy down low and it is more painful with full bladder. I'm not getting stinging or small urine amounts- no spotting or anything either. The ache feels like it was even in my right ovary this morning, now it's low down in centre. I'm on a 37 day cycle and only just started ttc, I'm not sure what it is?!