"confirmed by HSA bank and not my employer. Does that make a difference?"
No, it doesn't make any difference. TurboTax just has a strange way of asking for this information by inappropriately implying that the information had to come from your employer. All TurboTax really want to know is if any part of the amount reported with code W in box 11 was an HSA contribution for the previous tax year. It doesn't matter how you came to know that.
