In a recent team match my opponent surprised me with 1.e4 c5 2.Nf3 Nc6 3.Bb5 g6 4. 0-0 Bg7 5.c3 e6!?

I have looked in 3 different Bb5 sicilian books but none of them so much as mention 5...e6 which surprises me because the ...e6, ...Ne7 and ...d5 setup is very common in the Closed Sicilian and Grand Prix attack and feels playable here too. I'm not sure I reacted the right way. The game proceeded:

6. d4 (what else?) cxd4 7.cxd4 d5 (In the game I was a bit worried about 7...Qb6!? but planned to meet it with 8.Na3!? Nxd4 9.Nc4 Bxf3 10.gxf3 Qc5  but I'm unsure if I get enough compensation for the pawn.) 8.exd5 exd5 etc. The game eventually petered out to a draw.

I wonder if the exchange on d5 in move 8 was too kind. After all the pawn exchange opens a diagonal for Bc8 and black can develop pressure against my d4 pawn. Maybe it's better to preserve tension with 8.Nc3 or blocking the center with 8.e5.

What do you think?