I find 4 3 3 formations easy to beat by using AMC and DMC to get in between the opponents lines and deprive them of the ball. You would probably be better to use maybe 3 1 3 1 2 to start with and then experiment a bit from there. I have 3 teams from level 33 down to level 12 ,all use DL CD DR DMC CM CM AML AMC/ST AMR ST with an attacking mindset. My DL and DR also have DC as second position , DC has DMC as second , both MC have DMC as second ,AML AMR have the ML or MR as second ,AMC has ST and ST has AMC. Takes a bit of training but if you train position before advancing % it takes less training to achieve it. For the record all 3 teams are on top of the League with the worst goal difference being + 83.