OP, I guess I'll just repeat what others have said. But I must admit I'm not a Pooh-girl ti US standards.
I was 20 when I went for the very first time all by myself on a multi-day solo trip to
Disneyland. That includes a 12-hour flight. And a 9-hour time zone difference

I loved it. As if you're ever alone, you're surrounded by thousands of people! There is always a CM or someone in line you can talk with if you want to.
Last year at WDW, I did table service on my own, and loved it. At Coral reef, the fish kept me entertained, at 50PTC, the antics kept me entertained and at Plaza restaurant, I made notes about my day! If you want pictures,a sk one of the Photopass photographers, or just another guest. that's what I do, and I have met quite some nice people this way!
Do a Backstage Tour.
Do all the shopping you want.
Go on iasw 5 times in a row (if you want a picture of each and every doll, as I am trying to accomplish)
Eat 3 Dole whips a day without your family/ friends telling you you should remember your diet (I must admit I felt a little sick after the third one...)
The only thing I haven't done as a solo is a buffet. I'm too worried about leaving my stuff at the table while going to the buffet getting food.
Just go and enjoy yourself!
BTW, even if I'm there with my mom, I'm basically on my own, because she almost doesn't do any rides, so I always have to go on rides alone (she does keep my backpack then, lol)
Also, when I'm at the park with her, at some poinin the evening she goes back to the hotel before the park closes, and I always enjoy those two-three hours alone, because then I can go over and over on rides I like and she doesn't go on.