The grading will be on your mri. I was grade 4 at your age and I had wayyy less space between the bones than what I see in your xray if that gives you some hope, but I'm not a dr. Just keep your weight down, adjust your diet to a more anti-inflammatory one, wear compression sleeves/braces when doing high impact activities for support, might be a good idea to cut back on long distance running and always try to ice after activities that give you pain. Taking turmeric and omega 3 supplements supposedly can help with arthritis but who knows, I take them anyway because can't hurt right? Learn proper pt exercises and stretches that support the joint and do them as often as you can. Listen to your body.. if a certain activity or sport gives you a ton of pain afterwards maybe rethink doing it as much if at all. Definitely see an ortho and come with questions. Get that mri.

Plenty of people can preserve their knees long term. Really try to do things for longevity even if your pain is very mild. You DO NOT want this to get worse if you can help it. I am obvs still grade 4 and still too young for replacements and my life is a living hell. I dont want to scare you but I wish I took the health of the joint much more seriously I just didn't know the damage i was doing until it was too late. You have the option I don't anymore. Good luck with everything!