If a large piece of Wikipedia reference-linkmeniscus was trimmed/removed from you knee then there will be more 'play' in the knee as a result. This will be most obvious in flexion/rotation such as in crossing the leg. This is normal. Depending on your original injury you might have stretched slightly other ligament structures about the knee. This will add to the slight laxity in the same movement.

Your body will need to learn to move into and out of the extended positions of the knee over time. As you have only done this a few times there's a way to go. Your symptoms are normal so don't concern yourself to much. The movement should become more normal over time.