OPK Question

Sari • Married 7.5 years. Just had our first child, a baby girl on 4/20/16! 💗
I am new to this and am a little confused. I'm hoping some of you can help me. I am going on my second month off BC after being on it for almost 14 years, so I am still not really sure how long my cycle is or what is normal for me. I had a 31 day cycle last month, and from what I can remember, I was pretty regular before going on BC. 
 I got my AF on 4/26. However, it was pretty light, which I read can be normal right after stopping BC. It lasted 3 days and I spotted on the 4th day. I starting using OPK after AF ended and have mostly been using the dip stick Wondfo brand. Today I used Clear Blue Digital and got a happy face!!! Which means there was a surge. 😃  Can I be ready to ovulate this early in my cycle?? I also tested with the Wondfo brand a little later today and it did not detect a surge. Which is why I'm a little confused about what all this means. 
Also, I started using Fertilaid on 4/29. I don't know if this matters or not, but I thought I would include this information just in case.
The <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> says I'm not starting my fertile time until the 8th. But since I got that happy face with clear blue I started taking Guaifenesin today. I plan on taking it until the 13th, which is the time glow says I will be out of my fertile period. Do you think that is too long to take it?   
What should I make of this? Any comments would be greatly appreciated. Thank you in advance!