Positive test darker than control 3 days before AF

So I had my period last month and I am due to start my period in 2 days but for some reason yesterday I just knew I needed to test bought an 88 cent Walmart cheapie took it and there was a line instantly and by the time it was done it was darker than control. I was very carefully not to have sex 7 days before ovulation and 5 days after so I am shocked ugh..... is there anything else that could cause a positive test besides pregnancy? How the hell could it be that dark already? I have very regular 30 day cycles I don't think I was already pregnant as I bled for the 5 days 2 days heavy and 3 spotting🤷‍♀️ wtf