1) I'm so happy

Alex said that he was so happy

2) I drink a glass of water every breakfast

Alex said that he drank a glass of water every breakfast

3) I ate cupcakes yesterday

Alex said that he had eaten cupcakes every lunch a day before

4) I have drunk beer for two day

Alex said that he had drunk beer for two day

5) I had never drunk wine

Alex said that he had never drunk wine