Aww aren't you sweet!! I hope this is the month too!!
I use the internet OPK's too and I haven't had any trouble with them. Of course, as we know, everyone is different.
It is possible that since you've only come off BCP in April, that your body is still getting itself back to normal hormone levels. Sometimes it can take a little bit.
As for shift work... one of the girls on the TTC #1 board works shift work too and does temping. Her name is Casey (prayingforbaby1). I'm sure she'd be happy to answer any questions you might have about temping while having varying waking hours. She's awesome! I owe my EWCM to her this month!!