"I'm not good at orienting" isn't natural.
I think you mean "I'm not good at giving directions".
There is a sport called 'orienteering" and for this you can say, "I'm not good at orienteering".
Your 2nd sentence is ok. It is better to replace 'in' with 'for' and say, "If either of us are absent FOR the meeting, it wouldn't be good."
The 3rd sentence is ok, but very casual. Better to say, "She's ill, but she refuses to let me take her to the hospital."