I am literally back from the consultant and doctors because of my SPD and Sciatica. Done the physio (pointless) and have been having weekly sessions with the osteopath (financially crippling) since I was 25 weeks. I'm now 38 so the end is in sight but, like you, I'm flipping miserable.
Afraid the story is exactly the same from the consultants. Take more pain killers (co-codamol/codeine), rest, keep legs together as much as possible, avoid steps (we're in a second floor flat-happy days), no lifting, reaching, pushing (basically ANY verb-house is a total shithole because DH is oblivious to mess), sleep with pillow between legs, silk scarf to help turning over in bed when the pain on one hip becomes too much, straight back on couch (build a pillow fortress) etc.
If you can afford it, The osteopath did provide a little relief up to about week 36 but, to be honest, the last two sessions haven't touched the pain. Doctor has now prescribed cocodamol for daytime (4 tabs max) and dihydrocodeine (1tab max) to help me sleep through the pain. I know drugs really aren't the answer and I'd much rather not take them, but needs must.
Feeling your pain-hope you find a solution that works for you.