My tucked planche. Can't get raise my knees/hips higher (with pics).

As you see in the pics above, this is my current level of tucked planche.

I can maintain this position for 20 seconds. I cut them in 6 sets of 10 second holds. But I haven't been able to increase or improve my form (raising my hips/knees and going to an advanced tucked)

My goal is to have a nice flat back advanced tucked planche before Spring 2016. 

What do I have to improve to get to the next level (advaned tucked)?

Your shoulders are deffinitely not protracted. You simply cant tuck knees in when scapula is retracted becouse your feet would be on floor. Look down on floor not in front of yourself.

Get a mirror or film yourself so you can correct all errors easier.

Thanks.
I am been working on protracted holds and hollow body by doing planche leans as well as lying hollow body holds. 2-3 sets each before I start my tcuked planche sets.

Any tips to improve the form of protaction and the strenght it needs? 

If you cant hold tuck planche with perfect form then step back to planche leans. Doing planche with not protracted scapula wont lead to perfect planche becouse protraction muscles wont be trained.

Always lean into tuck planche and then lift your legs up from floor, dont just push yourself from floor. Good luck

You must learn the right form, in the basic tuck planche, your knees should be tucked in towards your chest, your hips should be at shoulder height and your back should be nice and round - not straight. Learn to protract and depress scapula, that is the only way to target and strengthen the right muscles to achieve planche.