I am confused if i had or not tear my knee acl as my mri states 'likely full thickness rupture' instead of stating a definite complete tear.

Can be hard: to tell if the tendon is completely torn on MRI. If your physical exam shows knee laxity (drawer test) then it is more likely the tendon is completely torn.

Agree w/ other doc: Sometimes we cannot be 100% sure the tear is complete. It is best if you have a MSK radiologist read your MRI, he or she will have the best chance of telling you. Regardless, sounds like you have a high grade tear and like was mentioned...then based on your exam and degree of instability and need to return to your level of activity; surgery needs to be considered. Good luck