There's not really a way to control them and YMMV. My boob growth has been bizarre compared to other girls here - like when I was on anti-androgens alone, I had the soreness, tenderness, and the breast bud, but now that I'm on E as well, I've had none of that, though I have been gaining weight and size steadily over the past year. If you want to have an idea of what size you'll end up with, look at your mom and your aunts(both sides), and subtract a cup if they have had kids. You'll likely be around there. If you're not happy having larger sized boobs, there's always gentle binding like the drag kings and the transmen do.