I looked at this move for the purpose of keeping the BK in the centre, but I don't think it stops Black castling in the (not so) long run, and Black has time now to bring the Q back into the action.

As Ion says this move not so good in long run, allows Blacks Q to pull back

Centralising. I think Black might now have a playable game...

I was looking at the bizarre move 12.Nd2!? ... with the idea 12...Qxg5 13.Qb3! Qf6 (13...0-0-0 14.Nf7) 14.Qxg8 0-0-0 15.Qf7 ... In this line White material is level, but White would have retained the initiative, methinks.

Nd2 looks bizarre but is definitely playable.

I would probably have done, too. True, the bishop is holding the Black King in the centre, but with the queens off the board, that might be so much of a consideration. By interposing the bishop White induces its counterpart to exchange - no bad thing for White - or to retreat. Either way, White loses no time.

I was looking at 14.Qf7ch as a finesse, with the idea 14...Kd8 15.Qxg8, but on reflection, that doesn't make any more difference than to waste a move. The idea was to avoid the defence ....Bf8, but in fact, that move now would have led to a quick checkmate. Instead the Line introduced by 14.Qf7ch Kd8 (goodbye castling) runs 15.f4! Nh6 (the Queen has nowhere to run that will mitigate the disaster about to befall g8 and a8) 16.fxg5 Nxf7 17.Nxf7ch Ke7 18.g6 hxg6 19.Ng5 and White gets away with an extra piece at the cost of a pawn.

No, but I develop a piece with gain of time.

In fact. after 14...Kd7??, 15.Bh3ch would be crushing: 15...Kd6 (15...Ke7 16.Qe6ch and mates) 16.Nf7ch K-moves 17.Nxg5 Rxg7 18.a3, White retains the extra piece, the position has been much simplified. and Black's counter-play prospects look much dimmer.

This is where is gets interesting. White Queen was under direct attack - but so was his King. He has to save both...

best as your N on d2 is binned and taking Qxa8 would lose with qxd2# checkmate You played correctely

Actually 16.f4 might not have been so bad an alternative, here.

Fritz prefers 0-0-0

Or 18.Bg2.

Fritz likes Bg2.

19.Qb3 at least carried a threat. Short ranged threats can be used to make progress, for instance, here: 19.Qb3 Rb8 (!?, say) 20.e4! Ke7 21.e5 when White's majority suddenly looks menacing. Black might be forced, after 19.Qb3 to consider whether it were not preferable to trade his b-pawn for time. E.g. 19.Qb3 Qe6 20.Qxb7 Qe3, say.

Fritz prefers Qb3.

Qb3 at this point seems best to carry on in place of trading Q's off

The split pawns doesn't appear to augur well for Black, but, vulnerable though can be in some respects, they can be a real nuisance if you want to convert your majority into a passed pawn. I think White still has an edge, but it must be a fairly slender one. I'd probably consider 20.Bg2 here, or, just possibly, 20.e4.

Fritz likes 20. Bg2.

Bg2 uses piece most effectively