I'm just about 21 weeks post op. Downstairs remains the big challenge for me. I do loads of downstairs, but I feel it almost every step. Spoke to my PT today who said the answer was one leg squats on and leg, bending a little at first then building up overtime. It takes ages, apparently, but it does come back. I think different folk progress differently, but it sounds like we have a similar issue at a similar stage in rehab ....good luck!
PT will be about agreeing a recovery plan for you and your needs. They will likely test how far you can bend your knee, and your balance and walking. The best thing I can advise is what people here advised me when I had the same question a few months back. Ask as many questions as you need to, and work with your pt and surgeon team, to a recovery timetable that is suitable for you.
And, I would completely encourage you to read posts here and ask questions. The folk here are phenomenally supportive and informative. It's been a huge help to me so far. I wish you well on your rehab 😀