Christina,
First of all, I want to encourage you that the end of Chapter 7 is challenging! Just keep on plugging, as subsequent chapters do have some ebb and flow in their overall feeling. Also, we discovered that once the story problem sets got much longer and were woven within the daily lessons, we had to downsize the numbers of those types of problems my son worked through.
This dawning came of course after we'd sent the World Geography Guide to press, as we hadn't gotten all the way through Foerster's I before having to make scheduling recommendations for the guide due to its press date.
So, anyway, what we did to keep our pacing going around chapter 8 on (after having a very similar moment to what you experienced in 7-10) was to first look to see if there were story problems at the end of the chapter, because in some chapters these were no longer there at the end. If there were not story problems at the end of the chapter, then we took the 2-3 days allotted for the story problems at the end of the chapter and added those days to the exercise days that had more story problems. This meant we could spend an extra day on a couple exercise days that were especially long in each chapter.
If there were still story problems at the end of the chapter, then we set a goal of no more than one hour and 15 min. of math work per day and planned accordingly. This meant that to save time on the heavy story problem days my son did some of the opening exercises orally, did odds for much of the lesson, and downsized the story problems. We didn't always do just the odd story problems in the exercises, as sometimes the story problems continued on to the next problem. Often, I let my son choose which story problems to do, but I did tell him to choose various types of problems (or he wouldn't know what was going on later). Then, on the story problem days we set the timer, and he worked until the time was up. Sometimes, he was done early and could do more problems. Other days he was done early, and I let him be done early.
On the regular exercise days (that didn't contain all of the story problems), we just did an exercise a day. On those days we didn't go until the time was up but rather just finished the exercise. If my son could see a lesson was going to go too long, he came to get me and we downsized as needed.
Foerster's is a great math text with wonderful incremental teaching. It is well worth the effort to complete, but as you head into these later chapters you will find some adjusting in the workload will make the program better for both you and your child!
Feel free to ask if you have other questions!
Blessings,
Carrie