The best indicators are to look at your parents and siblings, then perhaps auncles and niblings/cousins. Primarily the femme ones.

Then take a cup size less (especially if you started after the first puberty). Following that logic I'd be looking at getting a D... so yay?

You could also factor in the masculine members by doubling/tripling what they would have, but that's more complicated. Best to just stick to your closest fem relatives for comparison.

YMMY, though. It's highly dependent and the best way is to have a bit extra fat when you start on E. Assuming you start with a healthy weight: cycle each week: eat more, then burn it when you eat a bit less and sport more. Fat redistribution will then go faster. Helps to squat too (for the hips, belly and legs).

Do you get your levels tested, I had really shit levels on oral/sublingual and got like 10x the breast growth on 6 months injections than several years of pills.