Confused about digital OPK 😞

Ok ladies..... HELP! Yesterday was CD 7 for me. I took the Clear Blue Digital OPK and got a blank circle. Then this morning which is CD 8 I tested and got a solid smiley face! I couldn't help myself and I took the test again this evening (about 15 hours after the first test). But this time it was a blank circle again. Idk what to think. Did I ovulate super quick or was something wrong with the test? And especially since it's so early in the cycle! Do I count that as ovulating or should I keep testing?Β