My credit score has not moved for a year still 590 range and I've taken out credit cards and have made timely payments but nothing

I have two bills in collections. Which are old and can't do nothing about.
I don't have a mortgage, or car loan so I heard that's why it hasn't gotten up.
But I do have student loans and credit cards like about 4 all with like a 700 dollar credit limit with high interest rates obviously but I make on time payments on them and use them many times monthly for stuff like gas and products and I pay it back always on time and more than the minimum amount due. Still a year later my credit score does not increase. Why?

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