Hi Elhanan,
Thanks for posting.
Yes, your league makes a difference. Ideally, you should be placed around players similar to your skill level, which for you would mostly be Bronze and Silver players. It's a little weird that it's matching you up against Diamond as that's the second best group, but it might be trying to promote you, too, and demote the other player (Silver vs. Platinum isn't that much of a stretch).
We definitely have some very talented players in the group. I'm fairly good at teaching macro for all races, and I feel I have a relatively solid grasp on how it's all supposed to play out. I say "supposed" because I'm not the best player, but I have pretty decent predictions on what will happen in a match, and keep relatively good timing of what's going on.
Anyway, I can help you in two ways. You can either post your replays here and we can analyze them. Or, I can meet you sometime in game and on VoIP and discuss gameplay and such with you. I feel I also can help focus on more important aspects of the game that should hep you progress over time.