Gabrielle-
I completely understand what you are saying, and yes, I have been focusing on locking my knees. My hamstrings are also the tightest part of my body, knowing that, I will work on pulling down behind my feet with my elbows high. This is good to know:
“ONLY when your back is straight can you even contemplate straightening your legs. Most students should practice this pose with bent legs.”
Thank you!
Carly