The Power Clean movement is heavily dependent on form in order to progress the lift. Are you 100% sure that your form is solid - meaning that it's a fluid, singular motion from the floor? If yes - there are a couple things you can try. Rack pulls can help by allowing you to lift significantly heavier loads and at the same time generate more power in doing so, in the vain of the lower-middle part of a clean. Hang cleans can help to perfect the upper part of the lift - even if you feel that your off the floor form is perfect. Deadlifts can help to establish the off the floor posture and form, again, even if you feel that your form is perfect.
Now then - diet, rest and supplementation. Any forward progress made in lifting is half what you do in the gym and half what you do at home. Are you eating enough - and are you eating appropriate foods when you do eat? Are you sleeping enough? Lack of rest will kill progress every time.
So - there is a ton to look at. Take your time, avoid injury by using 110% good form, and get your nutrition and rest in line. Your loads will come up in time - be patient. Oly lifting is nothing to rush.