Since you are not doing annual passes, TIW is not an option for you. I agree with other PP, segmenting is an option, but it may be better to do it in 2-3 day segments, rather than every other day.
If you think you will return to Disney within 12 months of your arrival day, you could probably exchange your 7 day MYW tickets for an annual pass, since those MYW tickets have not been used yet. Then you could get TIW and use it for this trip and the one within the next year. You would not be able to get credit for the 2 remaining days from the previously used tickets, but you could save them for another time, since they don't expire.
BTW, you only save a great deal of $$ with DDP if you order the most expensive things on the menu. Plus, you are forced to get those little carrot cakes or chocolate cakes for most of the QS meals (the chocolate cake is yummy if you let it sit in the sun for about 15 minutes - warm chocolate cake - Mmm!). If you want an alcoholic beverage with you meal, you still end up ordering a NA-bevvy, since it comes with the plan. I think you may order fewer items overall, eat what you want, and spend less $$ in the end by paying cash or using TIW.