Help! Trying for a May baby

Need a little help with this one. AF ended Saturday. I BD Sunday. Took an ovulation test Monday that was positive. Took another test Tuesday afternoon and night it was negative. But BD anyway. Took another ovulation test weds. Negative. Did I miss my fertile window. Could I have ovulated the day right after my period?? I have also been taking folic acid and geritol liquid since July. Hoping for a May baby. Any thoughts? Help.