To increase height, you can put bed risers under the legs.
You mentioned that the height is a little high for sewing.
I am "assuming" that you are meaning you put your machine on top of the table, and thus your sewing height is probably another 4-6" above the table top. Some have used the pull out area of the table, and cut a hole to sink the table into that, to make the sewing surface table height.
Depending on the comfort/discomfort level, you could gain your extra height by using a higher chair, such as an adjustable drafting chair. That's what I use for sewing .... it's lowers level is about the same as the highest on a regular stenographer's chair. Plus the higher heights, let me sit right up to my cutting table when I want to work at it, while sitting.