Your yoga practice is exactly that. A practice. As someone who believed that you had to look a certain way or eat a certain diet to be a true "yogi", it was a liberating experience when I leaned that I could be a yogi at my own level. I have been lucky enough to have wonderful teachers who encouraged me to experience yoga at my own pace and celebrate my body and it's abilities in every pose.
Yoga class was the first time I attended a group class where I didn't find myself comparing my pose or ability level to everyone else's. Of course I noticed if someone was doing an impressive balance or a graceful Warrior III, but I was OK with where I was as well. I've learned that yoga is not about the final pose, but the journey towards the pose. If today your forward fold leaves you with your hands on your knees, that's great! Maybe after a week of practice you'll touch your shins. A month from now, your ankles. A year from now, your toes. Maybe your final forward fold will always be hands on your knees, and that's OK too! It is all about being empowered in your body and its abilities at any and every level.