Sorry for your situation. A couple of things, though. First, the parties don't need to "agree" on a QDRO. It is an order of the Court - and if the divorce was granted with a settlement of retirement plan rights, the judge can issue that order (a QDRO) without the parties doing anything to agree to it (you've already agreed to the amount and terms - the QDRO is a mechanism under federal law to actually get at retirement plan assets). It may be customary for the parties to agree (and at times easier to get a judge to sign it if they do), but it is not required. Second, your ex does NOT need to provide the data indicated in your original post. The plan probably has that info (it really should as a matter of federal law) - and as part of the plan's review of the QDRO, they will determine the amount - if it is based on a formula (like, 50% of the amount of increase between dates of marriage and divorce). If you provide the dates, the plan (through either the recordkeeper, or the Plan Administrator) should be able to figure it out. If they can't (change in employer through a merger or acquisition, or change in recordkeeper), then you can approximate the amount, and have the order changed to a specified dollar amount (rather than a formula). Finally, if your ex is truly necessary and still recalcitrant, the judge can 1) order them to not do anything with the plan assets until the issue is resolved; 2) hold them in contempt; and/or 3) penalize them, but simply awarding you the whole thing (rare, but I've seen it happen).
In any event, someone needs to get to the judge to "enforce that which was already ordered/agreed to." If not your attorney, then write a letter to the judge asking that the matter be reopened and reheard (and file a complaint with the local or state bar association responsible for attorney discipline). Domestic relations judges are used to that....