Hi, welcome to the forums!
If you haven't already, please read
Understanding Your FICO ® Score and
Credit Scoring 101 (at least the first post.)
These will give you the background knowledge you need to understand what you read here on the forums.
The high util on the one-and-only CC, plus the recent late, were definitely hurting you when you pulled your score. Scores?
First of all, to confirm, did you pull your score(s) from this site? Which score(s) did you pull?
With that out of the way, here are some ideas:
Sure, if your parents are willing to let you go authorized user (NOT joint) on two cards, that will be a temporary help; a stepping stone. The best card for an AU is:
-- older than your AAoA (average age of accounts) --easy in your case!
-- squeaky clean; no lates or any baddies of any sort
-- reporting a $0 or very, very minimal balance each month. <-- This means the amount due on the statement. Many sensible people wait for their statement to appear and then pay the amount due in full, but unfortunately, the amount due on the statement is reported to the credit bureaus and crunched for your scores. If it's a relatively high percentage of the card's credit limit, you won't get as much of a score boost.
In addition, you want to make sure that the card/ bank actually does report AU's. Speaking from my own and my family's experience, Discover, BofA, and American Express report AU's; PenFed and Gap do not. If you will post back on a separate thread titled something like "Do these cards report AU?", listing the potential card candidates, you'll find out which cards make a good choice.
A personal commentary on AU cards: these cards are mainly meant for members of a household who share expenses. For those of us who use them primarily to help our credit scores, I think that the honorable thing to do is to not accept a physical card, and to never ever use the account number to order anything online. If you had been using the card for some reason all along, that's different, but when people are gracious enough to allow you to mooch some nice credit history, I think it's a nice response to leave the card gathering dust in your sock drawer, and be happy with the history. I did get an actual card on DH's Discover, because I sometimes use it for our wonderful Honda mechanics, but I never use it otherwise. This makes me sad, because it's the Monet "Water Lilies" card design, and I'd love to wave it around...
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007