Weak Knees? Is this normal?

My Knees Have Always Felt Really Weak But I Thought It Was Normal Then In 10th Grade My Knees Started Giving Out Randomly So I Went To My Doctor And Turns Out I Have Slanted Knee Caps And Had To Wear Special Knee Braces To Support My Knees. Now I Go To Physical Therapy Twice A Week To Strengthen My Knees So From My Experiences I Think You Should Get It Checked Out By A Doctor.