I don't get how the field upgrades work, I've unlocked the anti-tank one and it says at level 2 you get 7 rockets, but I only have 5.
Do I have to keep playing with anti-tank to unlock all the levels within that kit or what?
Everyone starts with the level 1 field upgrade active frm their chosen path (defensive, offensive, anti-tank, etc). As you get squad points, from obeying squad order objectives, healing, resupplying, kill assisting, repairing, etc your squad members, your field upgrade bar starts to fill, and you gradually unlock the higher tier bonuses. However, if your squad gets wiped, your squad drops down a field upgrade tier. Your commander can also spend command points to promote your squad one tier. All of this is temporary per round.
It was intended to encourage squad teamplay and squad leaders giving orders to move as a unit. It's also why it is so frustrating to have lone wolf squad leaders that never issue attack or defend orders; you not only miss out on free bonus points for doing what you are already doing, it's much harder to unlock your field upgrades.