Charge off HELP!

Hi there, I needed some help with my situation. Back in 2007/2008 I had a credit card and I had delinquent payments. I was not able to pay them off for a few years and it was sent to collections. I didn't hear from collections in a while but in 2011, a collection agency (Northland Group) sent me a letter stating they would be willing to drop the amount owed (including charges) which was about 2,900 dollars down to about half if I paid in 3 installments or in full. I was definitely not able to do so but I emailed the agency asking if I could pay 100 a month since I would be able to afford that and they agreed. I have paid the amount ON time every single month since then and recently I received a letter (my balance was now 1,890.00) saying "As per your request we wish to advise you that your account with the above referenced client has been resolved. On belahf of Capital One Bank and Northland Group inc, thank you for resolving your account." What does this mean for my credit report? Since I have been paying off collections and have the bank statements to prove so. My credit report also says that the "Estimated month and year that this item will be removed: 12/2015"...It's almost as if I have been paying every single month for absolutely nothing. I'm a college student and I will have this charge off stay on my account for 2 years? I can't get approved for any credit cards whatsoever, can I even do anything about this at this point? I even have the letter saying my account was "resolved." I'd appreciate any help. Thanks!