A sweet and extremely helpful lymphedema therapist introduced me to Swell Spots. They are made to help "stimulate the lymphatic system directing lymph fluid away form the affected area and softening fibrosis" as you wear them. Swell Spot is a specific brand; she made me one and called it a "chip bag." Basically it's just a bumpy pad you wear inside of a snug bra. It seems too easy to be so helpful, but it really makes a huge difference for me. Below are links to the official Swell Spot, a video that shows exactly what the therapist made for me, and the foam I bought to make my own. The massage you are doing is great, too. In my area, an organization called The Victory Center offers all kinds of free resources to cancer patients. I do a class called Healthy Steps. It's a very, very low key exercise class with moves specially designed to help with lymphedema. It uses something called the Lebed Method, and is very helpful (and fun! It got me out of the house and moving when I really didn't feel like it, and the instructor and all the participants are wonderful and caring).

This is a Swell Spot made specifically for breast lymphedema. I'm sure it works great but seemed pretty pricey to me:
https://www.amazon.com/Swell-Spots-Small-Sobol-SP-06/dp/B002BUYKZI/ref=sr_1_1?crid=9APYEGRHD1N4&keywords=swell+spot&qid=1692186789&sprefix=swell+spot%2Caps%2C159&sr=8-1
This is a great video that shows exactly how my therapist made me my first chip bag:

This is the foam I bought to make my own (it comes as a big sheet, I just cut a piece to fit in my bra. When the foam gets worn and grungy, I just cut a new piece; the sheet is big enough to last a very long time):
https://www.compressionstore.com/products/medi-lymphpads
Actually, now that I look at everything, maybe I should invest in a real Swell Spot if they're washable. As it is, I replace my foam every few months, but since I plan to use a Swell Spot indefinitely, it might be cheaper in the long run to buy the official Swell Spot. You can DIY and see if it's helpful to you and then decide from there! I'll say again, I just can't believe how effective something so easy and simple and cheap can be (especially in this breast cancer world where nothing is easy or simple or cheap)!