You probably won't like my advice, but FWIW ...
WAIT to buy a house.
You've both got so much going on that there's no reason to rush into a major financial commitment.
WAIT until after you're married next month (congrats, by the way
). There's probably enough hubbub with the wedding that you don't need the headache of shopping for a house and running the gauntlet for financing and closing. Plus it doesn't matter how long you've been together, being married takes a certain period of adjustment.
WAIT until you've both finished grad/med school.
WAIT until you've each got an income that can support a mortgage payment plus all the costs that go with the joy of homeownership (repairs, maintenance, lawn, appliances, etc.).
WAIT until your credit scores are higher. Hers are good, not excellent. A lender will use the lower of a couple's middle scores, which will probably be yours.
WAIT until you can do this without Uncle's help. It was very nice of him to offer to cosign, but if he asked me for advice, I would say NEVER cosign. It will most surely lead to touble, and your family Thanksgivings will not be the same.
You're both young and you've got great futures ahead. Spend some time settling into adult life and then you'll be better positioned -- both emotionally and financially -- to buy a home.
JM very very HO.