If you are finding things tough don't worry that is natural. Often swimmers can have a preferred skill or stroke so focus on the positives and work on the challenges. Why not stick it out for another week or two or get back in the pool and practise this lesson content again. It is amazing how something that seemed so difficult at one point actually becomes the thing that delivers the most enjoyment, the sense of achievement overcoming obsticals is still one of the greatest feelings ever. Dont give up keep on trying.