If you are still living with your parents, do not say anything to them about you dressing unless you are pretty sure they will be accepting and open minded. You don’t need to be tossed out of their house unless you are ready to face the world on your own.
Since you are in your early 20s, I’m guessing your parents probably go to bed at a reasonable hour. When the house is quiet, watch YouTube videos (with headphones) for makeup and fashion tips and instruction. Then practice. If you need to buy makeup and clothes, I would suggest your local Walmart. Shop online and either buy online and pick it up at the store, or go into the store and buy it yourself. The Walmart app will tell you which aisle everything is located. The first couple times will be nerve racking, but you will quickly see no one really cares or is watching. And don’t be afraid to ask the sales women for help finding something. Just point to the item on your phone and ask where it is. Most of the time they will take you right to it.
As for purging… Just don’t. Years ago I purged too. Usually after… umm…you know…the thrill is gone. Instead of throwing things out, put everything in a box, tape it up and place it in the back of your closet. Out of sight, out of mind. Remember, there will be a next time.
One piece of personal advice: If you plan on going outside, wear what other girls wear. Garish makeup and slutty clothes don’t necessarily make you feminine. They may get you attention that you don’t really want though. Be safe.