I do not know what level is adequate.
What were the units for your levels? I got tested at Labcorp in the Seattle area. The first time, my levels were 45 U/ml; the second time, they were 55 U/ml. The “floor” was 0.83 U/ml, so the first time I had about 55 times the minimum; the second time about 66 the minimum. Did your test have similar units?
I had the same units. I’ve had one J&J shot and a Moderna booster. I was sick at thanksgiving with runny nose and everything smelling like smoke, but my COVID test came back negative - took the booster on Dec 1.
If you had covid and fought it with your own God given immune system, even if your antibody level wanes, for the rest of your life, your body will remember how it conquered the virus. Thus, if you are exposed again, you will never be as sick as the first time.