I'm not a doctor, nor am I giving you medical advice, I'm just someone with back pain issues that's spent a little bit of time reading about them.
You (and pretty much everyone else) should consider avoiding flexion exercises, primarily because they put unneeded pressure on your intervertebral discs. The fact that you are only activating one side of the spine is good, but not something I would personally do.
You might be interested in the research Stuart McGill has done on spine biomechanics. He's one of the leading researchers in the field and his book Low-Back-Disorders is a really good book to help understand spine biomechanics and what you should and should not do to maintain a healthy spine. It's all evidence based research unlike most work done on lower back pain issues.
Here is an except from page 45 of the Second Edition you might be interested in.
A couple of years ago we sought to most potent mechanism leading to disc
herniation. Given that it was critical to create a homogenous cohort of
specimens, we chose a pig spine model, controlling diet, physical activity,
genetic makeup, disc degeneration, and so forth. We found that repeated
flexion motion under simultaneous compressing losing was the easiest way
to ensure herniation.
While you are not loading your spine with your movement pattern, you are undergoing repeated flexion, which not really a good thing.
Here is another excerpt from page 155 of the Second Edition that you might be interested in because PT is typically done in the morning.
* Avoid lifting or spine bending shortly after rising from bed.
- Forward-bending stresses on the disc and ligaments are higher after rising
from bed compared with later in the day (at least 1 or 2 hours after rising),
causing discs to become injured at lower levels of load and degree of bending.
The reason for this is because your discs are typically more hydrated in the morning which will leads to more pressure on your discs when you engage in a flexion motion.
If you are not interested in reading medical texts, he has some YouTube videos you can check out as well, here is a good starting point:
https://www.youtube.com/watch?v=033ogPH6NNE
Hope you feel better soon. Disc issues suck, I know! :(