three things to say (they won't all be of help).
1. Thing that jumps out of your words most is your squad hasn't all blended yet. Too many signings all at once will disrupt the balance of your team and they will take a while to settle down. Set match prep to max on teamwork, in time, if the players you have are as good as you say they are, the second they settle down then you'll "buy" that win!
2. Are you sure the players are as good as you think they are? Take the time to select one by one the other squads in the championship, one of the things that surprises me most about this version's fm is how well the computer has actually started buying, the quality of other squads might surprise you. Take a real good look at your players without any preconceptions. Who says your signings are good enough to win the championship on paper? You? Your scouts? Your assistant manager? A few times so far I have had a reality check and had to accept that my signings weren't as good as I thought they were.
3. Tactics. Linked a bit to point 2. Re-evaluate your tactic. Who are your best players? What are their strengths? Is your formation really getting the best out of them? Where are your problems? Scoring or conceding or both? Creating chances but not scoring them? Not giving the opposition too many chances but leaking goals anyway? Do you have fast players or slow players (are you playing a fast paced game or a slow one in relation to them) A lot of this analysis should help in finding a new tactic to help you out.