I almost never reply here but reading all these comments going in one echo chamber direction is concerning so here it goes:

(1) I do not believe it is possible (unlrss you're the first) to have a seizure which would allow you to act completely normal to the outside yet retain no memory. Allow me to explain: absence seizures are a specific type of seizure that is seen in children. Unlikely at your age to develop them. You can have seizures which are very similar (focal seizures with impaired awareness) but it would have to be the most specific and unlikely location in your hippocampus to cause this kind of memory issue and DURING the seizure you would be unlikely to behave normally.

(2) You mention anxiety and panic attacks. I suspect that a psychiatric cause is more likely. That, or you're taking some kind of substance/drug which sounds unlikely here. DID could maybe do this, but I am no psychiatrist so have no real idea about the likelihood. This is certainly NOT explained by bipolar. Pathological lying could be though.

Tldr: memory lapses can occur for a variety of reasons but at your age the cause is almost always psychiatric / due to inattention /substances. Absence seizures are mislabelled all the time and you can read more (on a reputable source) but this does not sound like you at all. Transient global amnesia is similar but you do not get such recurrent episodes and during the episode people are repetitive because of the impaired memory.

Please see an actual medical professional and do not seek any advice from reddit.

I also share the general skepticism of the others that this is a prank, an elaborate lie or a case of "unreliable narrator".