Unlike child support, spousal support is often very difficult (if not impossible) to modify after the divorce is final, so getting it right the first time is a must!
Is the divorce final? How did it get final without you signing the decree? The only way I know for that to happen is if you went to trial and the judge made a decision which was not up to your lawyer to do anything about the decision unless you were ready to appeal it immediately (and 3.5 years of remaining silent is way to long for you to wait before needing a change). Or have you beein litigating it for 3.5 years without settlement? That would unusual. Like KGrow says, it's not possible for a case to settle without your signature, so there's something missing in this situation you're telling us.