No credit card required
Browse credit cards from a variety of issuers to see if there's a better card for you.
Well, it can only help. CA's are murder on the FICO.
High utilization (which you are above 50%) hurts too.
So, while nobody can guarantee what you will get, you will see some sizeable gains, based upon what you disclosed.
If the CA is the only one, it could affect your score anywhere from 20 to 100 points. I had a single $31 CA (error) that took my 689 to 806 when it was finally removed.