My right breast feels hard around the edges and is more painful when pressed. But my left breast is "mucho" (not saggy, I mean it's not hard like the other one), does this mean one is more developed than the other?

Yes, it's super normal for one breast to be different from the other, like one being firmer and the other softer, or even one being slightly larger than the other! Folks, our bodies are like that, we aren't exact copies, you know? This difference is even more common now during puberty, while the breasts are growing and developing. It's a process that takes time and is very individual for everyone.

What's Happening

Basically, breast growth doesn't happen perfectly symmetrically. One side might start developing a little earlier or faster than the other, which is why you feel this difference in texture and sensitivity. Hormones are going wild, and they don't send an exact message to every cell on each side to grow at the same speed, right?

And the Pain?

This tenderness when you press is also very common. It's because the breast tissues are growing and sometimes become more sensitive or swollen due to hormonal changes. It's like when you stretch and feel a bit of muscle soreness, but it's growth pain. If the pain is very intense, like it bothers you a lot and doesn't go away, then it's worth talking to a trusted adult, just to make sure everything is okay. But most of the time, it's just part of the process.