Hi hun, big hugs to you also. I suspect I could be heading for a similar situation over the next 12 weeks.
My thoughts would be to try and keep their routine now as close to what it will be after #3 arrives. It will be an adjustment period (obviously) after their sibling arrives, so the less changes for them probably the better.
In the meantime, I agree with the other gals - pick your battles and tread softly, softly for a bit while still keeping things on an even keel. You sound to me like you're already very tuned in to them, so that's got to be a real positive in your favour. Good luck for now and when bub arrives xx

(Now ... can I heed my own advice when it's my turn?)