Even if your husband's plan was not subject to division pursuant to a QDRO, there is still a mechanism for division, which is why you are now receiving benefits. You do not state when your divorce was finalized, but if you did not bring this issue up at trial, and your time for appeal has expired, you have no further remedies.
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You should speak with a local family lawyer about your issue. In all likelihood you cannot appeal the manner in which the pension was divided but you should check with local counsel to know for certain.