Thoughts on having another child

We have been trying to conceive since April 2012. To tell the truth, the main reason we started ttc was not exactly for the right reason. I contemplated having another kid but was not dead set on it (my son from a prev relationship will be 6 in Feb/13). We only really started trying and I went off birth control because our lawyer suggested that it would help our relocation case/ custody case if I got pregnant. But the longer we tried, the more sure my husband has become that he really really really wants kids. Me being obsessive by nature, I began charting my basal body temperature on fertilityfriend.com right away. 9 months later, we are STILL NOT PREGNANT! I am shocked because with my son, I got pregnant by accident, while taking birth control. I was 21 when I got pregnant. I know a lot of eating disorder stuff has happened in the last 5 years, but could that really be enough to make conceiving this difficult? I didn’t have my period for 3+ years and just got it back within the last year. I’ve been told by so many people that the moment we stop trying, that is when it will happen, but I don’t know how to “stop trying” or to forget about trying.