LLCs, S Corp and W2 Income

My wife and I are both employed full time (W2) + have a 50-50 LLC + have a SMLLC for myself.

Always used Turbotax for all taxes for the last 12+ years.

Questions

1. If we never filed a Form 2553, has our LLC been taxed as a normal LLC Partnership so far?

2. If our business income is not more than our W2 salaries, is there an advantage to classifying both our LLCs as S Corps? Or maybe just the multi-member LLC?

Any advice on this would be helpful.