Could I be prego or is it something else?

This month I thought I was starting my period but it all ended up being just spotting that lasted a few hrs. This was a few days ago no symptoms really I've had a headache all day and i had pain on my left ovary side for a little while but went away when the spotting stopped is it even possible or can it be something else? If not whats a good way to get pregnant fast and not miscarry this time?