Sort Surge

Can someone help me understand better. We've been TTC for 3 months now. Last month was my first months really tracking my ovulation. I used the Clearblue test that have just the control line and test line. On CD12 at 12:30pm I got my first positive (test line was the same color as the control line) at 6:30pm that evening I tested again only this time my test line was way darker than the control line. At almost mid night that same night I took a 3rd test and if it was positive it was barely positive but I almost feel like it was going to be negative within an hour or 2 tops. My first question is was the test I took at 6:30pm my peak. My 2nd question is if my Lh surge last only 12 hours does that mean I ovulated that same day. I had some mild cramps on my left side that night and into the next morning with a few times it being extremely noticeable.