Definitely real. She started out pretty young in the business and sometimes women don't fully develop breasts until they are in their college years (18 to 23). I had plenty of firsthand observation on that one.
Sometimes women's breast size also fluxuates with their body weight. Example: Gain weight like many women normally do during their 20's, and bam! Bigger tits. Also look at women like Ava Adams. Lost weight and tits shrank some. (Might have had a kid too.)
Just my 2 cents.