这是一个含有宾语从句的复合句.宾语从句是 I would be at your house at six o'clock.
宾语从句中 用的时态是 过去将来时(would+动词）.因为主句的时态是过去时（I said...),所以宾语从句作为间接引语,它的时态应该和主语保持一致.我说我将会6点到你家.
再给你个例子:She told me she would come.她告诉过我她会来.宾语从句中的时态也是过去将来时.