You don't mention how old you are. Age can make a difference.
25 years ago, i could sit any which way.
Today, I can still sit cross legged with my knees practically touching the ground, but it gets harder.
Approach things gradually, so you don't injure yourself.
The body is constantly reshaping itself. Even bones, which we think of as not changing very much, change.
Remember, it is the mind that meditates, not the knees,
so si6t in a chair now and then if it's easier.
Profile Picture: "The Foaming Monk"
The Chinese characters are Fo (buddha) and Ming (bright). The image is of a student of Buddhism, who, imagining himself to be a monk, and not understanding the true meaning of the words takes the sound of the words literally. Likewise, People on web forums sometime seem to be foaming at the mouth. Original painting by P.Volker /used by permission.