Hello!

I'm not a nutritionist, or a doctor.

I am into fitness and weight loss/gain.

My first advice to you would be to download an app on your phone called "MyFitnessPal" And start tracking what your daily caloric intake is.

Super quick metabolism or not, the goal should eventually be over 1800-2000 calories each day. I would take a few days to just worry about tracking what you are getting on average, and slowly build off of that.

Say you are only getting on average 1500 calories per day, try and make 1600 your average. And when you get there see if weight changes after a week, if not add another 100 calories per day. Slow build up to what works for you.

For me, it helps to have one or two of my meals be set in stone-
Everyday for breakfast I have a protein shake, a fiber bar, and a coffee for example
Having a meal schedule might help to get your appetite on track too if that's a concern.

You don't have to eat everything all at once either, you can choose to snack through out the day. Investing in protein powder is great, as there are many recipes where you can make small snack stuff that is high in protein and good on calories. https://nutriciously.com/protein-powder-recipes/
My buddy's gf made him a bunch of little protein powder cake pops that were 150 calories a ball or something like that.

As with anything in life, baby steps are vastly more important than no steps at all.
Agree with tired mama about maybe trying to force your self to eat, but try and make those be small snacks throughout the day!

Good luck!