Overall, I like the idea of this subclass. Psychic Strike could be a little stronger I feel, and Psionic Discovery acts similar to a Domain list that they've tried introducing in previous Sorcerer UAs without being overpowered. One of my biggest gripes, though, is with Psychic Sorcery. Whenever you need to cast a spell using psionics, you typically need to do that right now, as opposed to rolling a die, casting the spell, and seeing if you're able to do so psionically. I feel Psychic Strike might make more sense if you could use this ability automatically, perhaps by reducing the size of the die. 

I think Psychic Strike should allow a choice between having the extra damage be psychic or force (telekinetic). Might require a name change to Psionic Strike that being the case.