What do you Think? Could I be pregnant?

Hello I was wondering what your opinions are and looking some advice. On the early hours off Saturday morning I stupidly had sex without protection. He ejaculated twice in me. I had only just finished my period. I took an ovulation test today (Monday) and I couldn't really make it out I think it says not ovulating the diagram isn't the best. Today I am having really bad back pain and period pains and it's making me think it's implantation pains! I don't know maybe if I am overthinking it or not. Getting hot flushes to. I am going tomorrow to get the morning afterpill ellaone as I read you can take it 5 days 120hours after sexual intercourse. I just pray it works and it was a stupid one night stand thing. Do you think I could already be pregnant and has implantation already started? Can you ovulate straight after your period? Can you conceive 1 day after your period? I'm so worried. Many thanks pic off the ovulation test attached