Young Forward - Ademilson 5m
Young AMC - Wellington Nem 3.5m
both are Brazilian so you need to have that loaded but they both turn into cracking players and that fills two of your positions awesomely for 8.5m
LB - Santon from Newcastle or Alaba from Bayern as you've saved a lot on the first two.
CM - wealth of options, depends on the player you want. Capoue from toulouse for 13.5m is a physical beast and one of my favorites. Tachtsidis from Roma can also cover DM and turns into a beast. If you want to spend the money 15-19m for Romulo from Spartak one of the best DM/defensive CMs in the game.
Playmaker - Poli from Sampdoria for under 10m, he is basically the little pirlo imo. or Cirigliano from River Plate, also cheap and a great all around playmaker cm.