High thyroid antibody counts mean you have an autoimmune throid disease. There are four or five different ones, and often a person has more than one type.
Thyroid disease is very complex and diverse. There are over a dozen different types or subsets of thyroid disease, and different stages or phases.
Where you are right now with your condition is hard to say without test results and lab limits to look at.
You should ask for a copy of your last tests and see what the results were. You can often fall within lab limits and have "normal" test results but not be well.
It's possible you could be balanced right now and not need medicaion. If you have very few antibodies, it may stay that way for quite a while.
You should also be monitored every month or two because your hormone levels could change again, rapidly.
The thyroid med you were taking was to supplement the thyroid hormones your body wasn't making enough of. Thyroid meds don't treat the antibody levels, only control the level of thyroid hormones in your body. It sounds like the med worked a little too well.
Synthroid and other thyroid hormone replacement meds can be taken for life (in the case where the thyroid is removed surgically or ablated by Radioactive Iodine). Often, though, the same meds are given to supplement a "sluggish" thyroid that doesn't produce what your body needs to have the proper metabolism.
I'd keep a eye on your symptoms - the presence of the antibodies can mean more problems down the road with your thyroid levels. Antibodies can cause overactive thyroid (most often Graves Disease) or underactive thyroid (most often Hashimotos Disease). Or, there is a chance the antibodies won't cause any problems, you'll just have to wait and see.
Hope that helps you out a bit.