Can't understand my lumbar issues. Any ideas?

[SS2016]

So I herniated 2 discs (L4/L5 and L5/S1) back in march of 2014. It was initially due to an injury from sport which ended up with me hyper extending my lumbar on squats and deadlifts which finished off my back.
I started doing rehab with an S&C coach (pretty sure he unfortunately had some physical therapy degree as a lot of what he said sounded a lot like Kelly Starrett) from a supposed world class sporting rehab facility in august of that year. The exercises he gave me (front squats, dumbbell rdl (eventually onto block pulls) etc etc) tried their best to avoid as much lumbar extension as possible. He also told me to not squeeze my chest up when doing block pulls.
I did his rehab programme for a solid 6 weeks and my back felt pretty decent but had to stop due to sport and school.
My back started getting worse and the only time that I was free to go back to the gym was the end of summer 2015. After the first few weeks deadlifts were really hurting my back so I stopped them and continued with the front squats. My back was fairly iffy until October where I had to stop again, for school.
I got back to the gym in late January where after the first few deadlifting sessions, my back was really hurting me, no matter how hard I tried to keep my core tight, so I stopped deadlifting. I have been going to the gym infrequently (again, due to school), but eliminated deadlifts so as to save my back, until the last 2 weeks where I've been going 3 times a week.
I added in deadlifts. The first 2 sessions hurt my back but after that, the pain has pretty much gone away. There's still a slight bit of stiffness/pain in the morning but it's negligible to what I've been feeling for the last few years. My issue is that I don't understand why my back is like this.
Is it because, initially, the lack of hyper extension during deadlifts took a lot of the pressure off my lumbar which alleviated the pain but then, over time, my lower back was became very weak as it wasn't being trained, to the point where it was in kyphosis during deadlifts and I was setting myself up for posterior herniation of my discs then when I added back the deadlifts over the last few weeks and focused on more extension of my lumbar, my lower back has got stronger which has also helped alleviate the pain?
I'm really confused and just want to know what's up with my back so I won't get injured again.
Thanks
(also, I've switched from front squats to high bar back squats as I'm saving up for a SS coach to teach me how to squat and high bar squatting isn't hurting my back at the moment)

[Michael Wolf]

Condense the history and question to three or four normal length sentences and re-post.

[SS2016]

Back injury:
2 herniated discs from hyper extending my lumbar on squats and deadlifts
Rehab (started in sept 2014) consisted of front squats, block pulls and some other lifts - focused on keeping a tighter core and limiting extension of lumbar - got good results pain-wise after first few months but stopped going to the gym due to unrelated sports injuries and school
Been going to the gym sporadically (due to school) since summer 2015 but back pain hasn't improved (did same exercises i got from rehab coach)
Started going consistently (3 times a week) for the last 2 weeks but focused more on lumbar extension during deadlifts from floor and slightly during high bar squats (low bar form is poor and can't afford SS coach yet) - pain has gone down a lot

Question:
Did my back pain improve initially as limiting lumbar extension took a lot of pressure off my back but eventually my lumbar became weak (due to lack of extension). Since I was slightly kyphotic during deadlifts, my back pain got worse and I was setting myself up for posterior herniation of my discs but increasing lumbar extension recently has strengthened my back so a lot of the pain has subsided?
Apologies for the poorly worded q - just want to get a better understanding of my back

[Michael Wolf]

A little long still, but better.

Ya, I'm still a little unclear on your question, but from what I can gather, I think you need to learn to brace and set your trunk properly from all around - abs from the front, erectors from the back - without getting into any flexion or over-extension. This isn't very easy to teach over the internet, unfortunately.

[Darin Deaton]

Here's my take on it. I'm a DPT and SSC. Giving you my coaching opinion. The initial improvement in pain was most likely due to the natural, normal healing process and reduction in discal or surrounding soft tissue inflammation. In other words, as long as you weren't irritating your injury, it was getting better on its own. The increase in LBP maybe due to lack of strength and stability, poor mechanics or degenerative changes at that segment. The advent of using deadlift and squat, with proper form, increases blood flow to the tissue, increases the back strength, stabilizes the segments and develops the hamstrings to support the back. This can help, but it is dependent on the specific pathology. My recommendation, lift, take your time, gradually progress loads and follow the method, SS. Avoid quick power movements for a while or anything that increases LBP. If you can't afford a coach, read the book.