We as trans women are good at spotting each other. We know what the signs are, and we've got them in the front of our minds all the time. This is especially because we put a lot of effort into trying to mask or counteract the things that we can't change...the things we think make us identifiably trans.
The cashier that helped me at the grocery store tonight had all the classic signs. She had a fairly low voice, was close to 6 ft, had big hands, slight brow bossing, and a masculine shaped face. She was also
pregnant. So...not a trans woman. Not even a little bit.

It's really true that women come in all shapes and sizes. We nitpick our physical shortcomings, because we're afraid of being clocked or outed. But we focus on that at the expense of our self-confidence, and
that's what outs us more often than not.
So control the things you can control, mask the things you can't control as best you can. And then just enjoy the fact that you're not a guy anymore.