Herniated discs l4/l5, l5/s1, bilateral sacroillitis x5 years, chronic back pain and worsening leg weakness. Sick of pt, now what?

Sick of PT. Unfortunately, with your issues exercise is an important factor. Swimming is best as it can be low impact while keeping the joints moving. Si joints can be made numb with raiofrequency performed by a qualified pain doc and can last upto a year or more. Herniated discs too can be treated with minimally invasive techniques, esp if they are contained (the outer rim is intact).
Conservative failure. When disc herniation is found to be be the cause of progressive neurological deficit, surgical options should be discussed with a spine surgeon. This is likely your best option.