I think you're doing ok, thankfully for us the defenses prepared by Psy worked, though I am thinking if someone fails to get the lever in time or flying creatures we could have issues. I'm wondering why the Goblins spawned in year 2 and then I suddenly thought...did Paul set the mechanics workshop to repeat! If he did mechanisms generate a LOT of fortress wealth and whilst a healthy supply of them is good, you could possibly turn off the repeat and cancel the order to make the year a little easier.