My situation was very similar to antiquedahlia. I "forgot" (to be honest I had habits and did things that I didn't even understand why) and then, at the same age, glorious nineteen, it came back. It started as a single image and feeling...well, it's difficult to explain that feeling emotionally, terrified/dirty/hopeless/confused as ****....It started out as one and I pushed that ****er back. After all, that couldn't have happened to me, not me. I knew I was lying to myself, but I didn't care. Two months down the road, more images came up. More feelings and not just emotional. I began having phantom pains and severe panic attacks. Then the "daydreams" also known as flashbacks, and then the nightmares and then when I couldn't take it anymore I went to my school counselor and had one hell of a breakdown. She wouldn't allow me to leave her office until a trauma worker came in to evaluate me. After a few weeks, I was diagnosed with PTSD like symptoms. After two months, I was officially diagnosed with PTSD and through tracking both school and medical records along with observations from people who knew me then; it's officially concluded that this thing happened to me. I remember most of it now, but not everything. My T tells me that I dissociated during the event and may never get certain bits back. Nothing would make me happier. I should add in here that when I use quotations for "forget", it is because I always had a weird feeling and especially after the first time I had sex. When I had sex, I realized that it wasn't my "first time" but I had no recollection of having sex prior; I pushed my feelings down then, too.

So, it is possible to "forget", in some cases. Though, I don't know how common it actually is and I'm not qualified to tell you whether or not this is the case with you. I'm going to insist you see a therapist and hopefully get this all worked out.

Stay safe and take care. And welcome to PC.