No discredit to your instructor but he/she should be looking at where you look! Im surprised it hasnt been noticed?
It doesnt matter if youre landing a helo or a 747, looking the right place to maxmise the visual cues is essential.
Often, where to look, is not obvious.......so your instructor needs to teach you where and why.
As others have posted you need to get your eyes up to the horizon.
There is a certain 'feel' to where exactly your flare height is, so as has been mentioned, get your instructor to fly down the field at the ideal height so you can start to 'feel' where the ground is.
Lastly, you may find a cadence helps calm the nerves. The more we err, the more the nerves increase and then we get frustrated.
Autos & EOLs are great fun!
So, as you're descending, prior to the flare.....just say to yourself "3.....2.....1......flare"
The 3,2,1 will most likely not be regular at first, it maybe "3......2,1,Flare" but I promise you will find it benefits your judgement and calms any nerves wrt the ground rush!
I promise this very simple technique will work!
One other thing, try as your descending in the glide, stretching out the fingers off your left hand. Please do not let go of the collective, just stretch out the fingers.
I would guess, you'll be surprised at how tight your holding it?
Its a great trick and rediculously effective!
The flare itself is dynamic. It does matter if you've done 20 or 2000, you really dont know how much to flare until you're into it. With experience you'll become better at 'guessing' (with knowledge of weight, wind, density altitude, rrpm etc) but.......the intial cyclic input will always be just "your best guess".
You then of course adjust the attitude to acheive the groundspeed, run-on you desire.
I am very jealous. I know we all remember those days and the joy of learning to fly a helicopter.......Have fun and enjoy it.