The opponent you lost to was almost certainly cheating. I've been experimenting with the Nimzo-Sicilian at the 1900 level, and in over 70 games playing it to date, I've played the double pawn sacrifice line exactly once, against someone who was later banned for cheating! The odds of an 1100 even knowing that line, let alone subsequently outplaying an FM are so miniscule that I'm shocked they haven't been already banned!
these gambits can be very double edged. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Ok7atrisVgo.html if you don't play accurately then you just end up in a worse position down some pawns. this g5 and Bf4 idea is hard to spot. because you look at g5 and after they move the queen and the bishop is still defended you kind of stop calculating.
