Sorry that you're having troubles with this. As far as not understanding, just keep asking questions until you get the answers that you understand. If you don't understand what is going on or what is next, ask the question again. The doctors work for us, you need to know what's going on. If you need to take someone with you to your doctors appointments that can help decipher what they are telling you.
Now for the bone marrow biopsy, it's really not a big deal. Sounds much worse than it it. They lay you on your side and will give you a shot in the hip area to numb the area, as well as giving you either a shot or IV of a couple of other drugs to relax you and put you almost to sleep. They will put a syringe of sorts into your hip bone and take a sample. I had it done as well as countless other folks here on the site. Don't be scared of the test. It will show them if there is any activity that is abnormal in your bone marrow that is an indication of leukemia, lymphoma and several other types. So, yes, I think you need to do it if the doctors are asking for it. I wish you the best and hope you have a clean bone marrow test!