That would be great if you had at least 20% to put down, and a good work history, but since you are using FHA stuff, you may just need to get that credit card. I have ONE credit card that I use for online stuff, or QVC and the minute the bill comes in I pay it. I dont wait for the due date, I pay it the day it arrives in the mail. The same for car loans. They get paid BEFORE the due date. All of this stuff adds up.
Even a store credit card can help boost your credit rating if you cant get a convential card. Kohls, or Sears or which ever. Just make sure that you dont go crazy. Get $50 of something, and pay it off. you dont need $500 of stuff, even the small amounts show that you are responsible with the credit.
A debt to credit ratio is a tricky thing. They want you to show some kind of debt so that you can prove you have a history of paying it back ON time, or before time. That you wont go hog wild with a limit, and that you are using it as a tool, not as a life line.
Having ONE credit card can be a good thing. Debit cards dont count. Just never lose sight of why you have it and make firm rules about its use. NOTHING can go on it, unless you can pay it in FULL at the end of that month. if you cant meet that rule, then dont buy it. I use my sears card all the time for things like lawn mowers or TVs or whatever because it can net me an extra 10% off the purchase. I always pay it off, so I dont worry about what the interest rate it.
IM so proud of you!