So confused

On Monday I found out I was pregnant but my hcg betas came back at a 4, Tuesday Wednesday and Thursday my betas stayed at a 6 and I was told it was a chemical. Now it’s Saturday and my pregnancy tests are completely negative but I just took an ovulation test because I had a lot of CM last night and it’s positive! I am so confused because my hcg is back down to 0. What is going on?!