Have you asked your midwife to refer you to a physio? I got a band to wear with my first pregnancy which helped. Similar to you, start 20th weeks first pregnancy and was shocked how early it started second pregnancy. Heat packs on an evening helped. Sleeping with a pillow between legs. Got a physio appointment tomorrow so hoping that’s helpful 🤞
Birth ball helps me, no sofa sitting, no sitting in bed. Honestly it's so painful at night so haven't quite worked that out!