Help.. !?

Ok so here goes .. cd 15 got a positive opk about 4 in the afternoon .. about 8-9 o'clock he same night I had slight stomach cramps .. We did the deed the same night about 1-2 hours after the stomach cramps .. could the stomach cramps of been ovulation ?? If so we timed it just right didn't we? First month of using opk so not sure really when to go for .. any a dive would be much appreciated .. x