You are just making the "transition" from a big board to an intermediate board. We all have gone through similar problems as we progressed to smaller boards so there is nothing unique about this.
As for tacking the board, it's just a matter of moving quickly with no stopping at the front. It's just one side to the other on one quick movement. You can actually practice this with a broom stick (as a mast to step around) or you can practice the moves with your rig on the beach. Lay a towel down to simulate the board and get used to to the foot movements. After a few dozen tries, it will start to become automatic.
However, practicing the tack on the water will give you more practice uphauling when you fall off.
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.