Are anonymous online surveys exempt from IRB?
At least at my institution and I suspect at most of them, the IRB tells you when your survey doesn't need full IRB review because it is legally exempt (often through an expedited process). You don't get to skip IRB entirely because you don't think it's needed (unless your institution says this is the case, or sends you in an alternate path to determine exemption, like some other not-really-an-IRB-committee).
You also might be saved if you can operate under some sort of blanket exemption from IRB for a category of work. For example, courses for students might have such a protocol that allows review to be skipped as long as it fits in certain parameters (basically they've already gotten acceptance for a range of studies that fit those parameters).
You'll have to contact your IRB, and likely beg them for forgiveness. It doesn't matter what we think at all. See also here and another useful Q&amp;A that applies to your question.