Fusion is serious surgery and you run a risk of blowing the disk above the fusion as it will now bear a lot of the weight the ones below normally were handling. Learn all you can about it and what exercises you can do to keep your core as strong as possible so it doesn't happen to you.
I had discectomy 7 months ago. I hadn't ridden for the 13 weeks prior to the surgery going through all kinds on conservative treatments first. Took my first ride 5 weeks post surgery. Had surprisingly good power and was able to practically time trial at a good clip on the flats with no problem flattening the rollers; 8 miles total that day. Mostly did lots of walking after surgery (walked half a mile the day of surgery and 3 miles the next). At 6 week point, the sciatica came back and I couldn't have ridden out of my driveway. Next MRI showed inflammation and fluid so luckily no re-herniation.
It's amazing how complex and fragile the spinal system is and what can go wrong with it. Sounds like you are doing well now so that's good, and I feel like I am too. It's an absolute nightmare for some. Folks would do well to pay attention to how they lift and keep a strong core IMO. I'm 56 y/o and I did all kinds of wild stuff in my younger days but none of us can rewrite history
