FHA Guaranteed Mortgage and my down payment

[Mike]

Hello,first time user here and soon-to-be first time homeowner. Here's my question:I've been approved for a FHA ensured mortgage through Wells Fargo. I applied over the phone, recieved the mortgage package, filled it out and submitted and got my pre-approval letter back the next day. the loan I was pre-approved for was assuming my available funds would be 20% down on the loan.However, after reading about FHA mortgages, I realized that the FHA only requires a 3% down payment. Of course, I know the advantages of the 20% down, no PMI, etc.. BUT: does this mean that I don't necessarily have to put down all 20%? this is really limiting how much home I can buy, apparently, I qualify (income-wise) for much much more. but my down paymet is limiting me.So, who determines what my minimum down is? Wells Fargo, or the FHA?Many thanks for the responses