Tailbone Pain

[jay clock]

That video is excellent, and she also has her leg extended the right amount. Body position looks good too without being extreme

 

[Meg888]

 

[Pat "5mph"]

I lean to the left when stopping also, but the bike was just sliding away from me

On stopping and starting keep your brakes engaged (levers pulled) so the bike doesn't run away from you.
You're doing well, the shorts in the saddle thing happens to me too, but only the rare times I do wear padded

 

[Heisenberg71]

The other day I stretched myself fully backwards, right back over the saddle trying to stretch my back and shoulders. Hooked my tights in the back of the saddle and couldn't get them unhooked. Try stopping and unclipping in that position. I very nearly went down!

It happens to us all.

Practice the video tips, get your technique and then go for more height until you get that straight(ish) leg.
Keep going.