Currently wearing "super busty" G-K cup nursing bras, they are all too small. Please help!

I am at my wit's end trying to figure out what size I am in wire-free bras that don't use a cup & band size system. Measurements:

Loose Underbust: 36 inches

Snug Underbust: 35.5 inches

Tight Underbust: 34 inches

Standing bust: 47 inches

Leaning bust: 50 inches

Lying bust: 48.5 inches

The calculator says 36HH/J in UK sizing. Does that seem accurate? I'm 15 months postpartum and still breastfeeding, and my boobs are saggy af. Every single bra I have gives me uniboob and quadriboob. I can't wear underwire bras because I'm lactating. I just bought a couple Evelyn & Bobbie bras that I was really excited about, and both of them are way too small in the band but baggy in the cups (size XL) and I'm heartbroken. Am I just doomed to have saggy boobs forever because no bras will fit me??