Hi Sarah
This JUST happened to me. My nurse said "they" (insurance?) won't put you on oxygen until you drop below 88%. I was ok while sitting, but dropped during exercise (a short walk) to 85%. So they had me on O2 while exercising and sleeping. I turned in my pulse-ox machine thingy to the home health care company this morning from an overnight room air test. I have been on 2 liters of O2 nightly since I started IVs, but since my lungs are in better shape now, I bet I won't have to keep it up, until next time... (if these guys at work give me a cold I am going to strangle them!) LOL
Here at high altitude "normal" is around 94%, so with walking, I think you are doing alright.