Ovulation Kits

I need some advice on the whole ovulation kits thing. I tried them for two months and it said I ovulated but the line was hard for me to read weather it was dark enough or not. I was only taking them to make sure I was ovulating and didn't pay attention on the calendar what day it was in my cycle. Anyway, my sister is pregnant with her second girl and due july 3rd. She said that the month she got pregnant she ovulated early on the 11th day. So, I thought I would try the kit again to see if I also have been early. I had my husband buy the other two kits so I was unaware just how much they cost. He said they were expensive, but when we went to get one last night I found out that he meant $19.00 expensive for the clear blue easy! So, I bought answer for $12.00. The advice I am looking for is this.... Has anyone used the brand answer and is it reliable? It said on the box that it predicts your two most fertile days where as clear blue easy just predicts when you are 12-36 hours from ovulation. Did I make a mistake buying this brand?