what is going on with my body

teal elephants 💓

Im suppose to ovulate in two day according to my app and for the past five months its been on point with the prediction im on cycle day 16 and normal ovalate on day 18 the app says it suppose to be a high day due to the fact that I ovalate in 2 days but my test are still neagative however I always gotten postive in the past. Is it possible to ovalate normally and then have one month to you dont ovulate or ovlauate late