@radekm A few thoughts for you added to all the other stuff from my 68 years of experience. You are just entering the part of life where it becomes costly from now on to do young and stupid stuff. Just like you think to yourself, oh maybe not the "buff 'n' puff" deadlifts cuz they might hurt an older, rehabbed injury. Think of your whole body that way. Don't just protect the injured before parts. Protect the not previously injured parts too cuz you need them for many years into the future.
For example. My father had a spinal fusion operation when in his 50's. My older brother has had lumbar problems for decades. Lived on oxycontin. He's now in early stages of dementia. They both smoked for large portions of their lives. Me? I can do a hundred back extensions on a 45 degree back extension bench. I NEVER do any exercise that compresses the spine with weight from above. As in NO squats, free standing or machine. But when I last regularly was going to a health club (5 yrs before retiring to Texas) I used to love watching the young guys from the corner of my eye while I put 6 45# plates on either side of the leg press machine. Such a machine allows one to isolate quad work and completely protect the low back. Which is why I got to the place where I did 3 X 15 reps of 550+ pounds like it was nothin' but fun. But did I do that because I got my jolly's out of showing up young guys who'd injure themselves just trying to make that much weight move at all? Nope, course not. Surely you've noticed old folks who have allowed their leg muscle strength to dwindle so badly that they shuffle step just to make it through the grocery store hanging onto the cart. Now is the time when you give your body a lifetime of health so you are never that person.
Instead of giving in to being genetically weak in my lumbar back, I've worked at keeping my core strong for decades. Trying to keep from being crude, on any given day that strong core serves both me and my baby in a very important way. I suspect when you are my age, you won't want to have given up a bit of how important that part of life is either. When your body already looks like what most guys would want, and then you say you wanna turn your light up by a couple thousand watts, you are aiming for way into the top 5%. Good for you. Quality of life for life should be your goal. And being in the top 5% before you hit 40 works well. At 40 I was running about 20 miles a week. My BP 90/60 and resting heart rate of 60 like a rock. That cardio-vascular health then has served me well.
A few random ideas:
Commitment to flexibility exercises is way important. Choose any flavor (yoga, basic stretching, etc.) you like.
Donkey kicks with a little ankle weight are a great and often overlooked glute exercise.
If you ran that much you know the "feel" of strong quads and dense calves. I know you are petite and want to avoid looking "hunky." Do make health and strength more important than the fine tuning of an appealing feminine shape. It will serve your health much better in the long run. And anyway, there are lots of guys in that top 5% who think the petite, strong and athletic gymnast look is
super attractive.
I see you're a vegetarian. But do look at the science. Don't be fooled by the anti-dietary fat crowd. Watch some stuff on ketogenic principles. Learn about good cholesterol is the building block for all the hormones that are so important.
Next time you see a family doc for a checkup, get a thorough hormone panel so you will have a baseline for you. (thyroid, estradiol, progesterone, testosterone) You'll be very happy to have it someday.
Get to the place that a vertical sit-up bench at the gym is your friend. There was a time when I used to do my sets on one holding a 45# plate to my chest. Dang that was a fun time.
Wish you the best in your endeavors!