Yes, it's usually the clear and stretchy cm that is most fertile. It can be different for everyone.
Sometimes tracking cm can be confusing...especially at the start but once you track it for a few months then you will find a trend, it's a lot easier if your cycle is regular. I never ended up using opks or bbt because I thought it would but too much strain on ttc and the more strain and stress...the more difficult it gets. My suggestion would be to use them as last stitch effort. Maybe if you've gone like 9 months or so without being able to get pregnant.
3 months isn't long....it can take a healthy couple up to a year to conceive. Try "Deanna's Plan" that's on the first post of this forum. It could help you out a lot too.
SSBD! :)
I believe the clear and stretchy cm is the most fertile and you should get that shortly before ovulation. I find tracking the cm to be very confusing. I highly recommend opk's. They have worked great for me. I especially like the clear blue easy digital ovulation that can be purchased from Amazon in a 20 pack. These are the easiest to read, but they are a bit more expensive than other kinds. Others highly recommend charting basal body temperature which will let you know that you have ovulated. I haven't tried that yet. Right now I am happy with just the opk.