Any ideas?

So my husband and I have been TTC for 6 months now. This month we tried pre-seed and opk. I have 3 different apps to help track when I'm ovulating, and the dates were all different. So we BD the 3rd,5th,&7th of this month. Nothing ever showed I was ovulating with the opk. I've been tracking CM and the past two days have seemed more sticky than egg white. Yesterday and today I have been having cramps off and on, not bad but it's there. Some one sided, lower abdomen, and in my back. If I actually ovulated on the 3rd would it be too early to get implantation cramps? I'm not sure what's going on! AF isn't due until the 18th!