You have quite a few red flags. A mostly online relationship and marrying soon after meeting in person is a huge red flag. There is also his excluded child, the fact that you previously sponsored a spouse, that you are a low-income person on disability, that your spouse is from a country with a higher rate of marriage fraud. Individually, each of those is not such a big deal; however, add it all together, it becomes consequential.
What are your ages? What is the relationship timeline? When did you start chatting, visits, marriage etc.?
There is no law about time frames but fraud marriages tend to follow the same general pattern and unfortunately for you, your situation fits somewhat into that pattern. I am not judging your relationship in any way, simply trying to show you how it can be viewed from the outside.
The more you are aware of this, the more prepared you and your husband can be to address every red flag at the interview. Also, your husband should be prepared to openly and candidly discuss your disability in the interview.