Hey Bewsy,, I'm 2 years post mastectomy with auxiliary clearance, losing 17 nodes. My arm does get a little bit puffy, but I'm lucky that it hasn't progressed any further than that. I was referred to a lymphoedema nurse who showed me some lymphatic drainage massage that I do morning and at night, I also find that gentle exercise helps, and wearing a sleeve for any travel. Can't do much about it except manage it that way. If I have any treatments, I ask that they don't take my blood pressure that side.
Have a look on a lymphoedema website, as they have some clips that demonstrate the massage techniques. Also get yourself a lymphoedema nurse who can help you monitor the fluid in your arm.
Hope this helps, Trace xxx