MRI update... PT's welcome :)

[KnottedYet]

Sounds like you're going to PT, unless the protrusion is squooshing into nerves. (numbness, weakness, loss of control, intractable pain)

Imagine you have jelly beans with liquid centers between each of the bones in your spine. One of your jelly beans (the one between L4 and L5, the last two bones of your low back) has gotten flattened a bit and is hanging out a little too far, instead of being nicely centered and bouncy between the bones. Another one (the one between L5 and S1, the last bone of your low back and the start of your pelvis) is also flattened and hanging out a bit, but it also looks like the liquidy center of that jelly bean has oozed out some.

Bulges can slurp back into place when the pressure that flattened the jellybeans in the first place is taken away (a lot of that is posture correction and strengthening and rest from aggravating activities until healed). Protrusions can slurp back some or can stay put or can be taken out in surgery.

The tight hip flexors you got from all those sit-ups can aggravate bulgy stuff. (ask your PT about "anterior pelvic tilt" too, please please please.)

Be diligent with your PT exercises, the precautions they give you, the ways they teach you to get up and down from bed and in and out of the car, and the limitations they put you on. (even if they limit your biking!) Limitations are temporary to give you a chance to heal, so try not to "cheat."

Keep us posted!