Trying to get pregnant

My husband and I have been trying to get pregnant for the last four months and so far have been unsuccessful. It is so annoying that for the eight years prior to this, I was doing everything in my power to prevent pregnancy and now all I want is for it to happen. Thankfully my husband is very supportive and says that it will happen when it's supposed to but I am a HUGE worry-wort and automatically jump to that o-so-scary word "infertile." Yes I know, four months of trying is nothing compared to some but this really is just a vent because I am sad and frustrated. Has anyone conceived using an ovulation kit and if so what brand do you recommend?