Never force your knee to bend and cause yourself pain. That causes swelling and makes you stiffer. There's no reason for you to have to worry about having a MUA in August. You are just 1/2 through healing your knee. Even now, if I have a lot of extra activity I'll swell some. At 6 months it's perfectly normal to still swell. Your knee isn't even a preteen yet! You are worrying way too much. You are doing the things you need to do. Sure, you'll have some pain afterwards. That's what icing and elevating is for!
Even if your OS wants to do a MUA in August, you don't have to if you don't want to. It's your body, your knee and your say so! He is your employee. You are his boss, not the other way around. He can't force you to do anything! Please just chill out and enjoy what your new knee is allowing you to do. In 3 months, you'll be doing even more, and in 6 months you'll be happy to have your year of healing behind you and using that new knee!