I'm removing staggered immediately and taking stand + bite, you didn't include -2 from intimidated thus your staggering attack misses. Also, I need to review full combat from that moment now and I don't have time anymore (I'm at work). Please re-check.
My round 2 starts with swift action (migty wraps), stand, and bite (hits AC 35) which means you need another Fort DC 26
If you trip on OA, obviously it still misses Check the combat if you have time, apply your penalties and post summary, I'll post next time after lunch.