DEPO SHOT AND TTC WITH MY BF?

I started depo in October 2010 and was suppose to get my next 1 this January 18, 2011 but didn't. I started coming on my normal period starting in April and have had 4 normal periods since then...is it possible I can conceive now becuz I just had my period June 23rd and I bought a ovulation test my cycle is 28 days so wen should I start testing for LH SURGE???