Is it correct to say that all of our attachments and all of our negative patterns of thinking, acting and feeling are part of our lower nature?
Only negative attachments are negative. Some attachments are ego-based and not necessarily from our lower nature. For example, attachments from loving someone very much, such as your children or family, are ego-based.
Feelings that are negative such as fear, anger etc. are part of the lower nature. The lower nature is very apparent to most people. It contains greed and all the feelings of manipulation and control. However, as you work to overcome them, they become less obvious and more subtle. An example is the feeling of envy that can appear like the opposite: wanting someone to do well. But beneath the surface, in that feeling, is a hidden feeling of jealousy if the person in fact does do well.