Crossing over into 700 in the next 12 months should be very easy.
You mention that you have two credit cards and additionally a store card. In your closing sentence you summarize by saying that you only have two credit cards. Actually, from FICO's perspective, you have three credit cards. (That store card is also a credit card.)
Some stuff hugely in your favor:
* You have no negative information on your reports
* You three credit cards (all you need is three to drive a high score).
* You have no problem paying off all your credit cards.
First you should do is the thing you have already said you are doing. And that is to pay off all your credit cards. That is going to give you a big boost.
What I encourage you to do next is to make sure you have established a payment history on all three. That means to have used each of the three cards at least a little for a few months in a row. Since you are at high utilization, that's probably already been achieved. (You can see this on your credit reports where there will be a series of "OK" marks in the "Payment History" or "Payment Timeline" section. At least three OK's in a row is what I am thinking.)
If you have a payment history, then I would go all the way and make sure that two of the three cards report at $0 and the other one reports with a small dollar amount, like maybe $10. That means paying them down to that level a few days before the new statement is generated (that's typically when the cards will report their balances to the three credit bureaus). THe result is that you will have a low overall utilization (which FICO will love) and you will have most of your accounts having a zero balance (which FICO also likes).
After you do that, look at your credit reports to see whether all those changes have been made. A good free service for pulling your EQ and TU reports is Credit Karma. When those changes have been made, take a look at your FICO score. BTW, how are you accessing your FICO score right now? Through your Discover?
A final touch would adding a $500 Share Secure loan to your credit mix. People here can explain exactly how to do that. It will be very cheap and cost you almost nothing in interest, though you will need $500 initially to put up for security. That will also help you a lot.
If you do not think you will be needing to buy a car or a house in the next 24 months, it is in your interest (for the long term) to add 1-2 more credit cards right now. People here can explain why. If you think you might be buying a car or a house, it probably makes more sense to hold off and just focus on seeing how high you can get your scores -- nobody has to have more than three cards for scoring purposes.
