Opk question...

Cheryl • 34 TTC baby #1, married 3 years together 15. Still completely head over heels in love!!❤
Opk question... i tested yesterday morning, no smiley face just a circle (low fertility ) tested this morning and now it a solid smiley face ( peak fertilty ) there was no in between ( flashing smiley) ... Question is is that normal, has anyone gone from low to peak with out a middle?