B.B.
I have had laser hair removal on my underarms. Mine was done with a Sonata laser and I got good results from 5 treatments. I have fair skin and dark hair, which makes me a good candidate for laser hair removal, someone with different coloring may not get the kind of results I did. Results will also depend of the type of laser used and the experience of the technician using the machine. Most patients get 80-90% hair reduction from 5-8 treatments. But again it will depend on the machine. I'm not sure that 3 treatments is going to be enough to get really good results, but that would be a good question for the doctor doing the procedure.
If you have treatments and have hormonal changes (pregnancy, menopause, etc) you can end up getting hair back. I had my treatments before I got pregnant and went from having about 2 hairs under each arm to having nearly all the hair come back.
I have worked at a medical spa where we offer laser hair removal for the last 5 1/2 years, and these are the things I tell patients before they have treatments. Hope this helps!