Hello – There is actually no set answer to this question! It’s hard to say whether you should judge severity based on symptoms (heart rate, tremors, frequent bowel movements, lack of sleep, weight loss, etc.), based on antibody levels, or based on how far outside of “normal” your T3/T4 are.
In theory, someone with extremely high T3/T4 and high antibody levels should experience the worst symptoms, but each patient is unique, so this isn’t always the case.
As you get a feel for posting here, you can probably get a general idea of where your symptoms fall on the spectrum of Graves’ issues.