The sequencing seems to be bit off at foot strike. Your knee drive knee begins it's rotation before your throwing arm gets up to 90 degrees. Not getting to 90 is reducing the range of your external rotation. Also your hips and shoulders are rotating together. Additionally, your back has a bit of an arch in it through release. It needs to be chest out to improve your kinetic chain and keep the torque in your rotation. First, try to get to 90 on your arm before you begin to rotate your drive leg. You have good arm speed and intent. If you can get your chain in order you can build some velocity.