Could they be wrong?

January, February, March i had no period. We had been trying for a baby but no luck! I also had really bad acid reflux, sore boobs, strange cravings for pineapple. On April 1,2019 I was bleeding really bad in a lot of pain during that day. Went home that evening thinking my period was just coming back. I passed something. Went to ER doctor believe it was a miscarriage wanted to run a blood test. Blood test came back negative. Went to OB next day and she said it was just an overcast which was why I had no period. May and June I had a full period of five days. In June I was in a bad accident and had to have knee surgery. Since this time I have had a short period of 1-2 days and no other symptoms. I’m so scared that they could’ve been wrong and this could happen again. Could they have been wrong?