Can veneers be shortened 2mm?

Six months ago, my dentist placed veneers that are way too long and won't redo them. They affect my speech and other dentists have commented on the length. The original dentist offered to shorten them, but they would need to be shortened at least 2mm to look normal. There is 2+ mm of veneer available (theyre much longer than my real teeth). Other dentists say this could break the veneers, but the original dentist swears they can be shortened with no problems. I can't afford to replace. Thoughts?