Your legs look like they are still quite bent at the bottom of your stroke. They should be straight, or very nearly so.
To quote
Sheldon Brown on the topic:
I like to think that William Blake summed it up nicely 200 years ago when he said:
"You never know what is enough
until you know what is too much."
I suggest gradually raising your saddle, perhaps half an inch (1 cm) at a time. Each time you raise it, ride the bike. If it doesn't feel noticeably worse to ride, ride it for at least a couple of miles/km. If it had been too low before, your bike will feel lighter and faster with the new riding position. If raising the saddle improved things, raise it again, and ride some more. Keep doing this until the saddle is finally too high, then lower it just a bit.
When the saddle is too high, you'll have to rock your hips to pedal, and you'll probably feel as if you need to stretch your legs to reach the bottom part of the pedal.