Where is the gambit exactly?

This is not the queen's gambit, that's only after 1.d4 d5 2.c4.

Yes, it has transposed.

This is interesting, if you were looking for a QGD why not just be more blunt about it with 1...d5 and 2...e6. The way you played it made it look like you were playing for a Nimzo, but when you got it you went to a QGD instead. Nothing wrong with that at all, just interesting

This might be a variation of the Semi-Slav but I don't know a lot of theory on d4 openings so I'm not sure.

Gameknot describes it as the Lasker variation of the Queens Gambit Declined, although that normally continues with Nf6-e4 at some stage.

That's weird, as the Lasker is ultimately defined by bringing the f6 knight to e4. This position is the Classical/Orthodox variation of the QGD. However, both the Lasker and the Orthodox tend to involve a lot of exchanging, and therefore a lot of dull games.

I was fairly confident here. White scores quite well on the databases. Black has slightly weakened his kingside with h6. g2-g4-g5 was the long term plan, to open a file on the kingside. Unfortunately I never got round to this! Gameknot is still describing this as the Lasker variation of the Queens Gambit Declined. My good friend, brigadecommander says "First bad move by white..9.0-0-0??.Throws away the 1st move advantage." I'm not convinced, 9. 0-0-0 scores well in the opening databases

I can't agree with 9. O-O-O either, but it might be nice as a time to time surprise factor. Usually in the Orthodox, white likes to develop the LSB to d3, castle short, and play Rc1 since the c file tends to open in these games. From there, it's usually about keeping blacks breaks to a minimum and avoiding exchanges, since you already have the space advantage

I of course plan to keep lines closed on the queenside, and I hope to open lines on the kingside. I am following Cebalo, Miso (2544) vs. Zecevic, Dean (2288) which white won.

Post-game computer analysis gives this as a mistake and suggests a5 instead. This position is in the Gameknot databases, there is one game with this position, Cebalo, Miso (2544) vs. Zecevic, Dean (2288), where black continued with 11.....b4, white won in 33 moves.

Not sure if I would have preferred 13...Nef3 to prevent whits light bishop attacking

Sound plan, at the moment, black's light squared bishop is bad, it has a very limited scope. My good friend, brigadecommander says "on 14.Ne2?? white throws away advantage and now the game is = " I tend to agree with her.

Another sound plan!

Post-game computer analysis suggests 25. Rhf1 was a mistake and recommends Bg3 instead. It gives this as a continuation, 25. Bg3 f6 26. Ng6 Nec3 27. bxc3 Nxc3 28. Qxa5 Qxa5 29. Nxa5 Rxa5 30. Rd2 Bd8 31. Nf4 Kf7 32. h4, with black's advantage "only" 1.03, compared to 25. Rhf1 f6 26. Nd3 Nec3 27. bxc3 Nxc3 28. Qxa5 Qxa5 29. Nxa5 Rxa5 30. Rd2 b3 31. Nc1 bxa2 32. Nxa2 Ne4 33. Rb2 with 1.85 advantage.

Nice!

thank you l-d-j!

Instead of moving the knight on e5, maybe it was better to move the knight on b3 to give my queen a couple of flight squares and prevent this combination. I lose the knight on e5 for a pawn, but maybe this is not as bad as what happens in the game.