Your credit score isn't what's holding up your loan.
It usually takes 45 days, perhaps even longer, for escrow to close on an FHA loan from the time of acceptance of your offer. For an FHA loan, they require at least 2 appraisals. And they should pretty much agree.
We had to back out of escrow when the appraisals came in at $295 and $400K. The bank had to conference the appraisers to seek a common ground, but the low appraiser wouldn't budge. After weeks of trying to get a resolution, we gave up, and moved on.
Wells Fargo may have approved/pre-approved you, but by the nature of your FHA loan, it has to be reviewed by the underwriter who will base his approval on the results of the appraiser (and the results of any inspections you may have mentioned in your contract).
That's another question: was there a mention of a pest report, roof inspection, etc? If so, the underwriter may make it a condition of approval to complete certain safety and hazard issue repairs before he approves the sale.