I'm sorry to be posting again. Tell me if I get annoying

I'm just wondering if this is normal or... I don't know.
It's not like I've discovered feelings I've never had before. I've never felt female. At 11 (long time ago!) I heard about "sex change operations" and I seriously considered it. So now, 32 years later, all of a sudden it's time to make a change. And I sort of understand why I'm ready now but it's so strange. In some ways it's like someone flipped a switch in my brain. It's like now that I've decided to be true to who I am I am goign 100 miles an hour. I'm totally preoccupied by this and want to move ahead so fast. I want to throw away all my "girl" clothes. I want to experiment and figure out where exactly on the spectrum I fit. I'm telling people about it (so far so good) and in some ways it's freaking awesome. I am so, so excited to change my name. I'm thrilled I'm getting clothes I like.
But then, today, after putting on my new pants (men's pants) and my new binder, my mood totally crashed. It seems sort of stupid. I've lived with my body being female forever and now, when I can make changes instead of being happy I'm down in the dumps about it not being good enough. I can't get my chest flat enough. I'm too short. I have a girls face. Blah blah blah. A few hours ago I was thrilled. What the $#%@?
Is this part of the process? Am I going insane?
And I know someone will probably ask. I have a therapist. She specializes in PTSD and I really need that support. She is very open and accepting but she doesn't specialize in gender issues.