help me analyze

i have advanced and now play vs 1900 in real chess i think i havent done big mistakes but somthing still missing here

i am black

I think it's better to play 5 ... -d6, not let White advance the pawn 6. e5

Ditto to Albina_V's comment. There's a reason the top responses to the 2. Nf3 Sicilian for Black are ...d6, ...e6, and ...Nc6, and not ...g6: those usually involve a central Nimzo pawn that either represses e5 or allows Black to dissolve White's e5-pawn.

Bc4 in the Sicilian is usually a weak square for White's KB because usually the bishop first bites granite with ...e6, then loses a tempo to ...d5 or ...b5 eventually: another reason for an early ...e6, which you didn't play.

Then you moved both your knights multiple times in the opening before developing your QB or rooks. 

As a result of all those lost tempi and minor positional mistakes you got overrun in the center, were forced to put your knight on the rim, and got doubled f-pawns that exposed your king. That was enough to cause a loss.