Oh, I'm sorry you have breast lymphedema, too. My case is thankfully very mild, probably because my breast surgeon was so proactive. We did a baseline SOZO before my lumpectomy and sentinel lymph node biopsy, and then again after. It didn't detect any lymphedema, but the physical therapist who saw me also did a very thorough examination and noticed the beginning of breast lymphedema (I had minor swelling of the breast, and 'orange peel' skin). She taught me some exercises, but I honestly haven't done them for ages, because I now do a class called Healthy Steps, which has most of the same moves. The physical therapist also made me a DIY swell spot, and I just make new ones as they get grubby. Mine is about the size of a credit card, and I just randomly move it around to different spots inside my bra. I would like to order an actual Swell Spot that covers my entire breast, though. I also wear a tight-fitting sports bra at all times (I've always slept in soft bras with no underwire anyway, it's just more comfortable for me since I have big, floppy boobs). The PT did try using kinesiology tape cut into a long, octopus-type shape, but my skin hates almost all adhesives and it gave me a rash. I see my breast surgeon's NP every six months and she always checks out the lymphedema. As I lay on my back, she will do very gentle massage directly on my breast for only a minute, and we can see immediate results. I should do massage myself at home; I would guess only five minutes per day would yield great results. Here are some links to all this:

Kelly Reed is a PT with lots of great YouTube videos about breast lymphedema. Here's one that shows some exercises:

Here's one about DIY swell spots:

One about using K-tape:

And massage:

This is a link to Healthy Steps:
https://www.gohealthysteps.com
I'm still kinda worried about developing worse lymphedema because it can appear years after cancer treatment, so I also do easy things like getting blood draws and pressures done only on the unaffected side, and wearing a compression sleeve while flying. But the tight bra, Healthy Steps class, and DIY swell spot are doing great for me so far.

Good luck!