Ok, here's the deal.....first off, your age doesn't matter. As long as you are not a minor and can legally enter into a contract, you are good.
In terms of your score, it appear too low to qualify as is. In terms of your finace's score, it is great and she may qualify, but if she attempts to qualify alone, you cannot use combined income. And your joint savings can only be used if she is on the account or there are other gifting options that can be looked at.
Your best bet is to sit down with a local lender and have them pull credit scores, verify incomes, look at debt ratios, and give you both options separately or together based on the factual findings. Good Luck.