Postive then Negative!

I keep getting positive then negative OPKs! Its driving me round the bend! I missed a period in February - tookbmultioke tests all negative so I put it down to the fact that these things just happen. I had negative OPKs for a little while and now they keep going positive to negative for about a week 🙄 anyone experienced anything similar...

Top one OPK, bottom one HPT..