Why can't i get pregnant

May

First I'll say how blessed I am to have 3 little boys. Although we've had 1 miscarriage at 12 weeks. Anywho we've been trying for almost a year, with a little not trying to see if it just happened to help with stress. But still nothing. After my last c section my doctor discussed maybe doing a tubal ligation because I coded 2 and my last 2 pregnancy we're just horrible. Is it possible she tied my tubes and I just don't no. I no it's crazy to think that but I just can't figure out why all of a sudden I'm not getting pregnant. I've been so sad thinking ok this is the month and then my period starts. We do the ovulation test and I just lay with insemination in there over night (tmi) but nothing. I'm trying not to stress but I can't help but wonder if there is something I wasn't told. Has this ever happened. Or could my c section be a factor that maybe something wasn't out back together??