Probably won't help much, but if your DM banned warlock on the basis of being too powerful, he has a really skewed perception of what powerful is, and its highly probable that you could slip in DMM under the radar. Let me geuss, he thinks wizards are crappy because they're squishy, right?

Anyway, what are you looking to do? If you want to be a Mellee CoDZilla type, fighter type feats are good. Metamagic is good for any full spellcaster, and since you are just barely able to cast 2nd level spells, try Touch of Healing to celebrate. This really helps with the brunt of out of combat healing, especially when combined with the Vigor spells from the Spell Compendium.