Pushing Down on the Water
Hi, It seems that your right hand and arm (I assime your left also) are pushing down on the water throughout your 50m swim. That causes drag and lifts your chest. Watch Terry or other youtube videos of Early Vertical Forearm. Its not the easiest thing to master but it'll certainly help you streamline/reduce drag and swim faster. I agree with others, you need to be more patient with your stroke. The extension of your lead arm should be under water not above. You seem to have very good bouyancy so with a couple changes, you'll be knocking off big seconds.