Negative after negative opk

Lindsay • Married to a wonderful man! We got married April 4, 2015. We are now TTC #1 and we are super excited and very hopeful!
I have yet to get a positive on an opk....I'm feeling so discouraged. I've been ttc for 7 months--nothing compared to some of you amazing ladies. I just need some advice. I got the ones off of amazon that I've seen some people buy and rave about. Should I try something different?