Cold slam

-----We were bye at the 2. match and got 18 vp. At 3. match we played against another not experienced opponents and we got 25 vp. Our scores were better than our team mates and the most important board was this 6♥ board which was only bid by 2 pairs in the championship.
I had this hand at the first seat and opened 1NT.
♠A8------------Vul-------:None
♥AJ85---------Dealer---:West
♦Q852
♣AT2
bidding went:
W------N------E-----S
1NT----P-----2♣----2♦
dbl-----P------3♦-----P
3♥------P-----4♦
4♠------P-----5♥
6♥----All Pass
lead 6 ♦.

♠A8------------------♠K754
♥AJ85------N------♥KQT63
♦Q852---W--E----♦-
♣AT2-------S-------♣K875
I ruffed it and played A of ♠, ruffed ♦ again. Now I played K of ♥, K of ♣ and another ♣ South ruffed it and played A of ♦. Here is the position
-----------♠QT9
-----------♥9
-----------♦-
-----------♣QJ9

♠8-----------N--------♠K75
♥AJ8-- -W---E-----♥QT
♦Q8---------S--------♦-
♣A---------------------♣87
------------♠J6
------------♥-
------------♦AKJT9
------------♣-
I ruffed it, North pitch a ♣, and only chance was returning hand with A of ♣ in order to ruff a ♦. So I played ♣ and seeing that South can not ruff I claimed all making 6♥= +1460 .
If you look at the diagram after ruffing ♦ when I cash all of ♥ North is squeezed in black suits.

Now lets see the appropriate bidding and play.
♠A8-----------N-------♠K754
♥AJ85----W---E----♥KQT63
♦Q852-------S-------♦-
♣AT2------------------♣K875

W------N------E-----S
1NT----P-----2♣----2♦
P-------P------3♠-----P
4♦------P------5♦-----P
6♥----All Pass
West should pass if you play non-forcing stayman, East's 3♠ bid shows 4c ♠ and 5c ♥ with short ♦ because he can double 2♦ with long ♦. Now West has a wonderful hand against a stiff ♦ so cue-bid with 4♦, and the story ends.
If South bid 2♦ or 3♦ I should have played it in this line:
1.ruff ♦
2.K of ♣, and a ♣

---If you A of ♣ wins at the 3. trick you make the contract with cross-ruffs. However, South ruff your small ♣ at the 3. trick and now you have enough entries.
after ruffing 2 more ♦ you reach the position:

♠8------------------♠K7
♥AJ-------N-------♥Q
♦Q------W--E----♦
♣2---------S-------♣75

When you cash ♥'s opponents are caught double squeeze. North is forced to keep ♠ and ♣ and south ♠ and ♦. Nice slam board that should be easily bid and made.