tell me is my team good enough for the next season what should I buy??

[Tactician]

I also won the cup once, without "under-leveling" my team.
Played with a team 1 lv above.
But if you're playing continually vs teams with good quality and active managers, some time you won't have the favor.

Sure that when you face a lot of active teams, the task might be more difficult. But, I think the major problem is that strange 'behaviour' of the game. I have faced a decent number of active teams from one level above in the Cup this season. Beaten all of them, except for one draw and 2 losses, some not easily of course, but with the right tactics they were brushed aside. For one of the match that I lost, I did not have a proper counter. So, it is acceptable. Only the final that was really strange and can be classified as a definite anomaly. By the way, I have used the standard orders for the starting formation, including force-counter. It failed, and the other counter formation used as from 60 mins or so failed too. The game simply did not want me to win. The reasons must be find out though. Also, the highlights in that particular match was very strange as compared to what I usually see in other matches.