Like I said, here 90 degrees at 6 weeks seems to be what surgeons want, and many of our members have done fine taking longer than that.
As you go about your daily life, increasing activity as tolerated, your range of motion will come back.
When I felt like I could do semi squats, I resumed getting things from lower cabinets and doing the cat litter; when I felt ready to do deeper squats, I resumed pruning and weeding the yard.
Good PT understands the cellular and soft tissue aspects of healing and collaborates with us, doing a variety of modalities to help us regain optimal function - it's a wonderful thing! Unfortunately not everyone has connected with good PT so we feel obligated to point out pitfalls (cookie cutter approach, overly focused on numbers rather than function) and abuses (pushing, pulling, cranking on joints, using weights to stretch).
There is scar tissue, which is part of normal healing, and there are adhesions, which really aren't as common as some PTs think, and take time to develop. Most orthos and PTs call them all scar tissue.
If you ever feel hard lumpy or ropy stuff under the skin that's some scar tissue that may well be temporary. Massage with the fingertips, circular plus lengthwise plus crosswise helps to soften and break it up, as does gently stretching the area. I experienced this on both knees. It never interfered with my range of motion.
With the first, left knee, it went away with me doing massage a few times a day.
On my second, right knee, it's still there despite many months of me and a PT doing deep massage and contributed to some lingering lateral quad discomfort and weakness that I needed to address with a Good PT.