Fertile Window! Help!!!!

Kelly • Boymama of 3 💙
I am confused because Glow is telling me fertile days of these...see pic below. But other websites are saying 27th-May 7th. I am not sure what to follow and don't want to miss my window. 
​This month, starting tomorrow, I will be using preseed and taking a 12 hour mucinex pill everyday. I typically do not get ewcm so it's hard to know for me when I am actually ovulating. I have never used opk's but I can tell when I am ovulating because I get pain but just unsure when I feel the pain if ovulation is coming or already in the process. 
​Just scared to miss my window! Really hoping this month is our month for bfp
​Any suggestions?