Well, I am sure they're not large!
I'm not sure I could just come right out and ask this in real life, so here we are.
I am interested in how mine appear, as it's something I've never considered before. I am a slight build and over 40, although my boobs haven't really changed much over time, they are now definitely less taught and the nipples are lower down.
I take a small in bra tops and when I wear a bra (rare) it is something like a 32B. I mostly wear bralets in S/M/L sizes so I know the sizing means very little in real terms.
Also, what size/shape would you deem passable to go braless?
Certainly not in a tight vest like I wear here, but more suitable, thicker clothes? I wear this vest here as it shows the clear outline of my chest. I do not go out and about like this 
Have added one bare pic, the nip is covered at the blue line.
I always wanted larger boobs and think my own are quite unattractive, but have accepted my lot, and am certainly not interested in surgery or shapewear at this point in my life, but would love to go braless more often. In winter its great under a vest and thick jumper, but not so much confident in summer.
(images added, will ask to delete soon, hope this is possible!)