Pregnant?!

I’m not trying ttc right now due to only being 18 and going to uni next year. Right now I’m struggling with a very strong smelling urine. It’s absolutely disgusting to me and makes me feel sick. However, when asking my boyfriend if he can smell it, he’s said no one every occasion. Also, I thought about the possibility of a UTI , however, it doesn’t sting to urine so I don’t think it is. I also have been having stomach cramps and a migraine that’s lasted for 5 days so far. I’ve taken two pregnancy tests and they’ve both come back negative so far. What’s going on?