N Xed the 3NT on the assumption that they didn't have a ♠ fit, holding the following hand:
W laid down with 6 ♠, and the contract went +1, resulting a bottom for us. The correct line of defence was to run N's ♥ suit, which would result in -3, but I subsequently misdefenced and resulting in a +1 for the contract. The misdefence was that I didn't realise the partner was giving signal by leading an ♥A against a NT contract, which I didn't realise to drop my ♥Q, and as a result partner switched to ♣ instead.
Other tables' results including 4♥S+2, 4♦xS-2 and 4♠E-1.
I was shocked by partner's X holding no sure entry to run my ♦, thinking that's bad bridge by us, and partner told me that she Xed assuming that I would have a ♠ entry because, according to the explanation, I must have a few more ♠s, which I didn't have as W's hand didn't match the explanation.
1. Was there any damage?
2. If W did hold a ♥ hand, was the X foolish?
3. When the dummy laid down, was a ♥ run by N an obvious line of defence given that their misunderstanding was already shown?
4. Was I to be blamed wholly because I failed to drop my ♥Q under the ♥A led?
Also, a final question was that, I kept making obvious mistakes (including cutting my bridges to dummy, playing cards in an order that allowing them to draw my last trump out causing me losing control of my hand, forgetting to cash a side suit winner resulting in 3NT= with 10 top tricks, etc.) which wouldn't happen as a textbook practice. How can I improve my performance as, here, it's clear that my bridge knowledge isn't missing, but instead I fail to perform to my best of my knowledge.