Pregnant? Or something else? please help?

sooo me and my bf had unprotected sex right around the time I was ovulating and I was due the 18th of this month, I started bleeding on the 17th but wasn't like I'm used to, it kept stopping and starting and didn't last as long. For a while now my bfs noticed I have really bad mood swings, I can go from been alright with him then snap at him just like that. I'm always tired, i feel like I'm always sleeping but I never feel awake, I just don't have the energy to do anything, all I wanna do is just stay in bed. I keep feeling sick, not alot but every so often it'll come on then go. I seem to be going to the toilet more often, normally for me I only go for a wee about twice a day, 3 at a push but now I go more, today up to now I've gone about 7/8 times and I'm not drinking more than usual.