Advice needed..

Ladies, I have been on contraception for the past 5 years. I started with the implant which was removed Dec 13 and started having the injection that lasts 11-12 weeks. But at the start of the year I decided I wanted a break from contraception, I wanted to have a period as weird as it sounds. I have been with my partner 5 years and we have sat and spoke about what we would do if I was to get pregnant, neither of us have any concerns. So my last injection was Friday 13th February 2015 and I have still not had a period. I am just looking for some advice on when I should expect one and if I am fertile currently. I have had unprotected sex a few times and have recently been feeling wetter than normal down below. I did a pregnancy test a few weeks ago and it was negative but I've heard its possible for it to be too early to be noticed. Also my stomach its rock hard but tougher than normal. Sorry for the essay ladies, any advice would be appreciated. I will be looking to do another test next week. My problem is I don't have a clue when my cycle is and haven't known for years.