How long should a mid facelift last? Should I be having jowls after only 9 months?

The duration of the results achieved with a face and neck lift cannot always be accurately predicted. If sagging was severe, it will obviously take years before the condition becomes as bad as it was before surgery. If the natural degenerative process in the skin is occurring rapidly, wrinkling and sagging will also accumulate more rapidly. This is precisely when “tuck-up” or “spot-welding” procedures are helpful.
A facelift generally helps turn back the clock about 10 years in most patients, but it does not stop the ticking. Nevertheless, most patients look forever younger than had they not had the procedure done at all. The excess skin and fat in the neck and lower jaw is removed at surgery. Any slack seen in the post-operative period is a result of continued aging and breaking down of the skin that remains.  This could be advanced by poor skin elasticity, stress, or environmental factors (e.g. sun, smoking, etc...)
Had the surgery not been performed, the patient would have the “new” sags on top of the “old” sags, which were removed at surgery. Tuck-ups help maintain a youthful appearance in the patient who chooses to have additional surgery. Tuck-ups are generally less extensive, less expensive, and quite effective. Addressing the SMAS during surgery is one way to help ensure that the best results possible can be obtained.Be sure your surgeon is a board certified facial plastic surgeon or plastic surgeon.

Lane10,
Thanks for your question.  A facelift typically lasts several years (10-12 years in most people), though you do not seem to be getting these results.  Giving you a "better" answer really requires analyzing pictures of your face before and after the surgeries you have had as well as a more in depth discussion about what about your face makes you unhappy, as not getting the results you want can be caused by several factors, and looking at photographs of your face over the past few years of surgery would be much more helpful.  Good luck!