I had and still have that issue too. Trust me you can move forward with your knees bent. You just have to teach your body to do it. It will come all in good time. Be patient and just try not to get in your own way mentally.
Bending my knees and lowering my center is a major issue for me. But one day it occurred to me that I was making excuses and telling myself I can't do it and getting in my own way. I still do it sometimes but less often now. I will make the excuse to sensei that I just can't do what he is showing me. He is so patient. Just smiles and says you need to lower your center and he shows me again...
When I stop saying I cant and start saying I'll try... I tend to discover I can do a lot of things that I really believed were not possible.