Thought I'd add my thoughts:

would agree with checking out piriformis syndrome - lots of glutes and piriformis stretching as tight glutes and piriformis will put extra strain on sciatic nerve (particularly piriformis as the nerve runs right underneath the muscle/actually through the muscle in a small no. of the population).

Just because the bulges aren't 'prolapsed' or impinging on the nerves as reported on the MRI doesn't mean this translates literally functionally. Most people with disc bulges find that they are aggravated with lifting / repetitive or prolonged flexion and eased with extension (and repetitive extension) which encourages the disc bulge to decrease.

Be very careful with posture - good posture and lots of core stability work is essential. Avoiding repetitive movements and prolonged positions, especially lumbar flexion is important. Would suggest addressing muscle tightness (piriformis/glutes/hamstrings) and lots of core work and then re-assess.

Obviously important to trust your physio as cannot diagnose and assess thoroughly over internet. If piriformis is a problem then self-friction massage (or from physio) will help as will heat and lots of stretching!

Hope this helps.