Bilingual to me means "speaking the later-acquired language as well as one speaks one's native language"; I hover around that level in German, depending on how long it is since I last spent time there (used to be at that level all the time, but after twenty-four years of living in a non-German-speaking country, most of the time I'm "just" fluent, which to me means something like "able to speak confidently without stopping to think about how to express oneself and without major grammatical errors". So from what you describe, I wouldn't say you're bilingual in ASL, or even fluent - but given what you were able to accomplish, I'd probably describe you as "competent". I'm around that level in French, and working towards it in Spanish, with a vague goal of being fluent by the time I do another Camino with boxcat in five or six years' time.