Your fears are not unfounded. In order for her to issue a valid pre approval letter to your builder, it has to be based on your CURRENT credit status, not on what she thinks it will be in a few months. Work on your credit FIRST, get your scores where they need to be, and you will eliminate any unwanted surprises at the end. Your mortgage approval is not based on score only. You must also have a certain number of you ESTABLISHED trade lines as well. As a former mortgage banker of 16 years, there are too many variables to list for your credit requirements because they also vary depending on which particular program you will be utilizing for your financing needs. I would strongly suggest that you use a different lender, one that can be factual with you, not suggestive. Or, get a second or even third opinion on the matter......until you are comfortable with the person guiding and assisting you with your purchase.