I'm sorry to hear you are having a crappy time ttc. It really is hard work - I remember the sex-ed chat at school and was terrified of falling pg by accident - well I know now that is rubbish!

It sounds like you roughly can pinpoint O day, so like Tiff said, try to do it as often as you can - sperm can live in a fertile environment for up to five days.

Just remember - you aren't out until AF shows. GL