At this point I think I'd wait and see if dropping the meds makes a difference in her behavior. A few weeks off her thyroid medication won't have appreciable affect--hypothyroidism in dogs is a much less severe than the same condition in humans and it may take weeks before she starts to gain weight or show other symptoms again.
How long has she been off the soloxine now? Has there been any improvement? If, after the two weeks she's still not back to normal, it may be that there is a different issue causing the aggression.
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."