First time buyer with 650 credit score

I'm looking to buy a new house, i got my credit score and it is 656, and now i'm making 72K a year, last year filled my tax on 62k, already got pre-approval from a broker and it is Up to 300K, FHA loan putting down 15K...my question is: will the number i have from the broker now change when i go to get the loan, i'm afraid to be shocked and can't put any offer for any hidden reason...

Thank you

There's no reason for him to lie to you about what you're approved for, otherwise it's just wasting everybody's time and nobody gets paid if you can't get financing.  If you've been honest and upfront about your personal information then the approval should be solid.  Is there a reason you don't trust your broker?  I would advise everybody to talk to a few different lenders/brokers to find a good fit for their personality and someone they trust. 

A lot depends on how you have proceeded with the loan application.  In your situation, you should have completed the loan application and all disclosures, provided the lender with all Income, Asset & Reserve information.  The loan officer should have submitted all of the info to underwriting and should have a decision.  With a decision he can give you a written commitment defining the terms of your loan and any conditions which still need to be completed.

With a written loan commitment you should be fairly safe.