Weird Symptoms, Negative Urine Test

I have a regular-ish period and I'm in my early 30s. I got a flow/red period for one day then some spotting for like 3 days after mid cycle. Then when I was expecting a period I got spotting instead and my breasts were tender before and during. I tested negative by a doctor urine test about 5 days before I was expecting my period and on 2 home tests after I got spotting instead of my period. Has anyone had this happen and found out they were pregnant later on? I'm super confused because I've never had this happen before and the doctor said I should still be too young to get perimenopause yet and I also don't do hormonal birth control either.