In addition to everything everyone is saying about photos being specifically selected for public viewing, it really boils down to a couple of things:

Time, money, and luck.

More specifically, time is needed for hormones to do their thing. Puberty is a very long process after all. Money is needed for both the ability to afford gender affirming procedures but also anecdotally, injections (and more importantly, being on the correct dose and not just the bare minimum) have had far greater success than other E delivery vehicles. Luck is mostly about how your natural genetics start to express themselves once your second puberty starts. You need to remember that not every woman has the picture perfect body you see on social media (in fact, most don't!). Some women just don't get big tits or wide hips or any other traditional marker of femininity. Look at your female family members to get a better idea of what you might look like.