Teeth Too Small for Braces? Is This True?

27 yr old female with a history of gaps in family. My gaps are throughout not just the two front teeth. I went to the dentist she advised my teeth are too small for braces...and they would eventually spread back out. Anyone ever hear this? Dr. Suggested if I wanted closer teeth I would have to get veneers because my teeth are so small, but then I thought braces then a retainer would keep them together. Please help! Also, would lumineers be a good option for me? Thanks in advance!