I play the Exchange Variation against the QGD, but I'm really struggling against the Tartakower style setup in the QGD, when black plays b6 and c5. As White, I just don't really know what I'm supposed to be doing against this setup. In the normal Carlsbad structure of the Exchange QGD, I play for f3 and e4 or a minority attack but neither seems to work in these Tartakower structures.
Here's a position that I've reached several times:
r2q1rk1/pb1nbpp1/1p3n1p/2pp4/3P3B/2NBP3/PPQ1NPPP/R4RK1 w - c6 0 12
Do I play on the queenside? It seems pretty difficult since black frequently plays c4, a6, b5, and is better on the queenside. Do I play in the center? This just seems impossible. I don't really see how I'm supposed to do anything on the kingside either, since pushing pawns would only expose my king. Taking on c5 doesn't seem to help since after black recaptures with bxc5, I still don't know what I should be doing.
Here's an excerpt from a game of mine (opponent and I both about 1900 FIDE) arising from an 3...a6 QGD:
r3r1k1/1b1n1ppp/pp1q1n2/2pp4/3P4/2NBPN1P/PPQ2PP1/R2R2K1 w - c6 0 14 1.Bf5 c4 2.a4 Rac8 3.Ne5 g6 4.Bxd7 Nxd7 5.Nxd7 Qxd7
At the final position in the diagram, I feel like I've already messed up. Black has a space advantage on the queenside, attacking prospects on the kingside with g5, g4, rook lift to h6, etc. I reached this position thinking it was okay because of Black's "bad" bishop, but the bishop can just be rerouted to f5 and be situated on an excellent diagonal.
What are some of the plans/strategies that White has in these types of positions?