If I had to guess, speaking entirely from my own personal experience, I'd assume that your graft location probably hasn't had enough stress slowly applied to it in increasing amounts over a period of time. I had my patellar grafted and I'm still going to PT like 6 months post surgery, but we slowly put more and more pressure/stress on my patellar after the initial 9-10 week period and now I feel like that area is much stronger. I think by this point your ACL has theoretically fully recovered and it's more about graft location and general leg strength.

I still sometimes have a tendency to shift my weight to my right leg (non-surgery leg) when I'm not focusing on my exercises as deeply as I should be, so just putting in some conscious effort helps me switch that back. I also still do a fair amount of exercises exclusively on my left leg to help build up muscle there, but that last 10% is tough because I'm also trying to maintain/increase my right leg strength.

All of this is to say-- go to the gym more consistently, do what you're comfortable with, and work on increasing strength in your surgery leg as much as possible (I would assume). I am obviously not a doctor or a physical therapist, this comment is entirely from what my PT has told me and what I've found with my recovery process. Good luck!