Welcome to the forum!
As an 18 year old, you have plenty of cards. $3k in real credit. You would be best advised to not get any more cards, to just work with the cards you have, keep the utilization down to minimize interest costs.
The danger of getting more credit now, if you already have high utilization is that you will carry larger balances. That means more interest cost, so everything you buy becomes more expensive. Your budget gets stressed, and that is the wrong way to use credit.
Better to pay down what you have, get used to only charging what you can PIF, keep interest expense at zero, and only borrowing for a particular purpose using the good credit you are going to be building, such as potentially financing a used car, later on, through the CU at a low APR.
