it make take a few months before your body goes back to normal and you actually ovulate. it would be silly of you to expect it to happen right away, even if you werent on birth control previously and knew how long your menstrual cycles were.
but, the rule of thumb is that a woman ovulates 14 days before her next period is due. so.. if youre going to maintain a 45 day cycle, then you would be ovulating around day 39. which would be tomorrow! so.. definitely spend some alone time with the hubby today and for the next few days =) your most fertile days are the day before ovulation, the day of ovulation, and the date after ovulation. they are basically the only days in your cycle that you can become pregnant.
also, the pregnancy hormone generally doesnt show up on a home pregnancy test as a positive until about 10-14 days after conception. so, unless youre having a shorter cycle this month, i think it is too early to test.