Going up or down in the course of a song is not unusual. Try to improve, but also remember you are in good company. Remwember a certain famous family whose surname began with W and ended in N, now ably represented by a young lady whose surname begins with C and ends in Y? Well, I have a feeling that if you listened to some of their early recordings, and listened out for what key the first and last verses of certain songs were in, you'd be surprised!