Worried I am Delusional. Please Help.

Let me start by saying that I have seen a therapist and told her everything I'm about to type now and that she did not think I was delusional. However, I do have severe OCD and I can't get the fear out of my mind. I'm looking for opinions from people who have had delusions and people who can offer support because this fear is seriously taking its toll on me.
This is my story and I apologize in advance for the length:

In January of last year I was having really bad health anxiety and my latest worry was that I had dissociative identity disorder. I went to bed one night trying to think of any times in my life where I've had amnesia about events or displayed another personality, and I couldn't think of any. So I went to sleep. At 5 am I woke up, because I suddenly remembered a time when I HAD displayed those qualities I was worried about. The memory was set in my first year in college, when I was browsing facebook and suddenly came across a profile that I knew was fake (because it used a fake internet picture that I used to use when I had a bad, regretful period of making fake social media profiles due to low self esteem in middle school). I clicked on the profile, and was shocked to see that this person was located in an area where I grew up and talked to people who I knew. Suddenly things about the fake profile seemed familiar and I realized that I must have made this profile in middle school and didn't even remember it. I was horrified and remember slamming my computer shut and trying to push it out of my mind, as it brought back a lot of guilt.
Anyway, that was the entirety of the memory. This is what I remembered at 5 am and I thought that I would get up and immediately check it out again on facebook to see if I remembered anything more about it. I typed the name of the fake profile I remembered into facebook and nothing came up, so I typed in a few other variations of the name and nothing came up.
Then I had the most terrifying thought ever: What if this is a delusion? What if this never happened?
....and I've been freaking out about it for the whole past year. I honestly don't know if it happened or not, all I know is that when I first "remembered" it, I believed it 100%, until the name search revealed nothing on facebook. I still have a very clear memory of it, but the more I think about it, the less likely it seems. I honestly think it may have been something I dreamed that night, but again, I'm not certain.
My OCD since then has had the theme of false memories, and worrying that more memories I believe to be true aren't. Since that original incident, I've had 10-15 other minor similar problems. For example, one day I was brushing my hair and "remembered" my younger sister saying she liked the blonde streaks in my hair. I have dark brown hair, with no blonde streaks, so it doesn't make sense for it to have happened, but yet it feels like I remember it happening. A second example, once, the day after I had to cancel a therapy session, I thought I remembered my therapy office sending me a letter in the mail asking for a reason for the cancellation since it was within such short notice. I knew as soon as I had this thought that it didn't happen, yet it truly feels like a memory.
My old therapist suggested that they were fleeting thoughts that could have been fragments of other memories or bits of dreams that pass through my mind and since I'm so afraid of remembering something incorrectly, I interpret it to be a memory when it is really an obsessive thought.
Other than these 10-15 occurrences in memory lapse about non-major events, I truly do have a great memory and believe my reality to be in tact.
I do experience major anxiety about EVERYTHING, and my greatest fear is losing my mind. It seems like the less I worry about having a false memory, the less it happens.
Do you think I could be delusional or is this really OCD playing tricks on me?

Please, does anyone have any advice for me??

I don't think you're delusional. Even if what you were saying was true, those would be hallucinations not delusions. Delusions are sincerely-held beliefs that are firmly maintained despite being contradicted by what most people accept as reality. My mom has delusional disorder and she believes she's working for the FBI and a whole lot of other things that don't make any sense, totally different from what you're experiencing. I think your anxiety and fear is just getting the best of you. If you were having delusions, other people around you would be telling you that what you believe is not real.