Is all of this spotting normal? Could I be pregnant?

About 3 weeks ago, I started to spot. It was a light brownish/kind of red. It lasted for a couple days. This happened after I had sex with my boyfriend. Then last week it happened again the day after we had sex. I have irregular periods. I usually get them every month and a half or two. Its been about a month and a half and I havent gotten my period. We use condoms so I don't really think I am pregnant but you never know. What is all of this spotting? When it happened 3 weeks ago, I had a UTI and i know that when you have a UTI you can have blood but it lasted for a couple days. Now again, I took a home UTI test and it shows positive. I have them so often, I'm beginning to think that from last time I had it, it never went away. But could that be the reason im spotting? im so confused :/ Im going to the gyno tomorrow but I kind of want to know what to expect.