However, when there's wind, the wind gradient forces me to adjust the speed, therefore I can't keep the reference point in the same place visually because of the attitude change.

Dropping the nose to increase the speed will make the glide slope steeper, and that will make the reference point move towards you such that you will land shorter. You should be using the spoilers to control the glide slope (possibly in combination with a slip).

So if you need to push the stick forward to increase speed, you also need to close the spoilers to correct for the steepening of the glide slope caused by the increase in airspeed. In this way the glide slope and the reference point will stay the same.

Now in practice at your stage of flying, you will push the stick forward, then as a second step you will close the spoilers to 're-aim' the glider at the reference point. Closing the spoilers will reduce the drag a little, so as a third step, you'll need to pull back slightly on the stick to maintain constant airspeed.

At some point in the future you will learn to ease the stick forward and simultaneously close the spoilers slightly, such that the glide slope stays constant (the reference point stays constant) as the speed increases.

I'm wondering why you're needing to increase speed on final. Should it be needed, you should trim for a higher than normal pattern speed on downwind leg, while you're high above the ground, before you've flown into any low level wind shear, and while you still have plenty of altitude to recover from a wind shear or tail gust induced stall. Then set your spoiler setting, and try to adjust the shape of the pattern to account for your glide slope and hit your reference point.

There is at least one legit scenario where you need to increase speed on final. If you're on final and have underestimated the needed pattern speed, you hit turbulence, and you lack sufficient control authority to keep the wings level. If that happens, you need to increase speed to regain control (higher speed will give you more momentum and more control authority). Again, when you push the stick forward (or as the second step), you also need to close the spoilers somewhat to maintain (or reestablish) the needed glide slope.

Both the stick and the spoiler handle should be moved in a smooth continuous motion. Never jerk the controls, especially in turbulence. Keep in mind that opening spoilers increases the stall speed and reduces airspeed (due to increased drag). To avoid low altitude stall, some pilots habitually push the stick forward before opening spoilers. You should at least check your indicated airspeed before opening spoilers.