TTC With PCOS

I stopped bc in april and got my period in may but i haven't gotten my period since then I went to the dr and he gave me Metformin. I've been taking it for 5 weeks and still no period.. All this week I've been having cramps on my left side and lower back pain and I've been peeing more frequently than usual. I took a hpt and I think its bfn but maybe its too early to test because I don't know it when ovulated or if I ovulated.. Can I be pregnant and its too early for a hpt to detect?