Hi again Charlie M.
OK, I think I see some "issues" here.
The Gaastra Freetime 6.0 is a school/trainer type sail.
In the 6.0 m2 size it has only 4 battens (not very much info on the Gaastra website
regardng the Freetime).
Without any specifications on what mast the 6.0 Freetime was designed for, it's a bit hard to tell how compatible your Freetime is with your Fiberspar 430 cm IMCS 21 mast, but that would probably be about the right specs.
Unfortunately, the Freetime is designed for fairly light winds, as a school/resort/trainer type sail so it most likely does not have the range (windspeed)or stability that a fully battened rig (like the Gaastra Pilot, an entry level sail with 5 battens and pretty much the bottom end of the Gaastra freeride full performance designs) would have.
So, I would guess that the Freetime simply may not have the stability you need for higher winds.
As for the front hand "push", my guess would be that you are spreading your hands too far apart on the boom, moving yoru front hand a bit too far back on the boom, and pulling way too hard with your back hand, resulting in being oversheeted.
And, as your instructor suggests, you are heading too high upwind.
The front push is most likely caused by the sail basically stalling as the wind starts to get around your mast to the lee side of the sail.
I completely agree with your instructor that you need to learn to sail at lower angles.
Some of this may be due to instability in the rig, but other factors may be that you are getting your weight a little upwind of the centerline of your BIC Nova 180 and this is causing your board to want to head upwind all the time. If your board "tips" upwind at all, it will turn upwind because that's what tipping it upwind is telling it to do.
Are you using the optional small center fin in your Nova?
This would cause a significant change in the techniques needed to sail your board at lower angles and contribute to your board "rounding up" alot.
Next time you are out with your board and rig in higher winds, after you uphaul, step back to get both your feet behind the mast BEFORE you put any power in your sail.
Then with the mast or boom (grip it right near the front please) bring your rig across the board until your mast is upwind of your board's centerline and upwind of your front shoulder.
Now reach FORWARD (not out) right in front of you back shoulder and put 2 fingers over the top of the boom about a shoulders width behind the mast.
Rotate your entire upper body just enough so your board begins to move forward on a beam reach (directly across the wind on the easiest point of sail).
Only rotate enough so that you power the sail up!
Only the amount (5 or 10 degrees here) required so you feel a nearly equal "pull" on both your front hand and the 2 fingers of your rear hand.
Resist any temptation to rotate your upper body more, or "pull in" with your back hand.
You should sail easily across the wind on a beam reach.
As your board picks up speed, you can sheet in slightly more.
If you let go with your 2 fingers on your back hand the sail will "sheet out" a little and the power will go away.
So, only sheet the sail in enough to put power in it.
Resist the temptation to rake the rig back and pull the sail in more as either of these will cause your board to want to turn upwind and stall and creating the front hand "push"
If you feel any front hand push, release the boom completely with your back hand, and bring the mast more upwind across the board to steer it off the wind a little.
Try sheeting in by rotating your upper body again and see if you can get your board to accelerate on a beam reach.
Resist the temptation to rake your rig back and sheet in all the way like other sailors with better rigs and skills.
You are sailing on true wind.
They are more advanced and are sailing on apparent wind which changes the wind direction and increases it's speed.
You will "get there" soon, but for now work on just steering further off the wind, and getting your board moving well.
Your Freetime (and all other WS sails) make two kinds of power.
The first kind is good and drives you and your board forward and is found with the sail well sheeted out (like around 45 deg. on a beam reach).
The 2nd kind of power is "not so good" and unless you have the skills to take advantage of the wind shift and increase in speed that comes with sailing the apparent wind, it will simply try to move your board sideways downwind, and also "load you up" with a lot of force that isn't doing you any good unless you have apparent wind skills.
Hope this helps,