The issue with attending a general spectrum yoga class, especially without your teacher being informed about your disc bulges is that any forward folding (flexion) could exasperate a bulge.
Now, there are yoga Asana (poses) that are extremely helpful for disc protrusion, however, they should be done in isolation, not in a general class that also includes a forward fold.
Any deep flexion, especially with a rounded back, could potentially turn your bulge into a full prolapse.