That's an achievement to advance to final of both CL & Cup. Hope you will have good results on finals.
I am a 35T no investment manager. Although I just reached the finals of both CL and Cup for once only, I believe a balance team with full squad is definitely capable to complete all 3 competitions at the same time. Even if there are many many injuries near the end of season, my green packs are still sufficient to ensure all startup players are almost full fit in games.
You're now at level 4. You may find the opponents much tougher when your team promoted to higher levels. At higher levels, there are less robot teams. The managers are smarter and have many experiences to carry a team to promotion. It will be more difficult to handle multiple games per day, especially that I like resting my not-in-good-form players.