One thing I noticed was that you go backwards a bit, which (I think) will make it harder to keep your balance and make the height suffer. Usually (again, I think) the back wheel will land in line with where it took off where as yours go backwards a bit. Also, with the backhopping bit that's been said, try doing a single pedal kick then sidehop. This is usually how I do them, the kind of pedal kick where the rear wheel doesn't leave the ground, and I find it helps as it makes it easier then trying to keep balanced then hopping. Although that may just be me, sorry if this is gobbledigoop.
And how long have you been using the Trialtechs?