There's a lot of mistakes everywhere, but clearly Black took the advantage in the opening and for most of the game I think Black was winning.
At the final position, Black can take White's Bishop with check so clearly he his winning. Maybe it's still a draw, but it's very unlikely.
By the way, 9...Nxf3+ 10. gxf3 Qxd3 11. Bxd3 Bxb2 wins on the spot for Black.
And you missed (at least) two good moves:
18. Bxe5 simply wins
and 11. Bd4 Qxd4 12. Nxd4 Bxd4 would have been interesting, with a Queen for two Bishops and two Pawns.
I think you should learn how to play the opening better.
3. Be3 was bad, you should develop Knights before Bishops.
4. e5 was also bad, you're just loosing time with a silly Pawn move... Again you should have developped a Knight.
5. Qd3 does nothing except loosing a Pawn, and you shouldn't move your Queen in the opening. 5. Nf3 or 5. exd6 were better.
8. Be2 just lose a second Pawn, and I would have probably resigned in this position.