Hi Island Girl, first, I commend you for wanting to take a wonderful trip with your daughter. I'm retired and I'm taking my 45-year-old daughter to Scandinavia in July of this year. As you noted, the summer is not ideal, but it's the only time that works for her, so that's when we're going.
As Judy has pointed out, it does help to put nights instead of days, as you get a more accurate idea of how much "real" time you have. It's much more accurate when you say that you will be there for three nights, so we know that you will have two full days and possibly a portion of the day arriving and maybe a portion of the day when you leave. Although most people tend to transfer to their next destination fairly early, so I wouldn't count on it.
I admit I'm a little confused by your schedule, and it might help to clarify that for us. The first part of it makes sense. Starting in Amsterdam and staying there for 4 days, then going to France for 6 days, it looks like 10 days right there.
But that's where the confusion starts. First, I'm a little unclear about how much time you're spending in Paris. You have written "Amboise to Paris; Paris to Frankfurt, Frankfurt to a German town, 1-2 days" (I'm paraphrasing that a little). Can you explain where you are and where those 1-2 days are spent? Are you just going to Paris to connect to Frankfurt from Amboise? Is there any reason that you're not spending time in Paris? I noticed that also in the beginning where you're going from Amsterdam to Paris and then to Bordeaux. Again, skipping Paris?
Honestly, it seems somewhat sacrilegious to me to go to France and not spend any time in Paris. It's such an incredible city. Of course, you may have a reason for that. Maybe you've been there before extensively and don't feel the need to go back? Just let us know because it does help us to help you.
Then you're going to Frankfurt for one to two days, and it looks like you have a day trip to Krakow and Auschwitz from there? Is that correct? I figure that must be a mistake because Kraków is about a ten-hour train ride from Frankfurt. And also the Prague itinerary is confusing as well.
Bottom line, with 18 days plus travel time, I would limit my countries. I would keep in France and keep in Amsterdam, and then pick one more place to go to. Whether it's Krakow or Prague or some place else. I don't know that I would choose Frankfurt. Frankfurt is a very nice city, but there are many more iconic places in Germany that you could visit.
For example, if you are looking for a sweet German town, you might want to try Gengenbach in the Black Forest in Germany, as it has a number of advantages. I stayed in Gengenbach several years ago, and it was just an incredibly beautiful town, with half-timbered houses and charming scenery. It is frequently called a "chocolate box village" because it is just so lovely. It has a good amount of hotels, cafes, and restaurants. It is on the main train line, so you can get to many other places from there quickly. It has the advantage of sitting on the border to France, so after leaving Amboise you could head down to the Alsace area and cross over to Gengenbach.
Plus while you are in Gengenbach, you can also make a day trip to Strasbourg in France, which is only 35-40 minutes from Gengenbach by train. Another advantage is that you will get a KONUS card if you stay in Gengenbach, which entitles you to free public transportation to most of the towns in the Black Forest area. From Gengenbach, you can head back up to Frankfurt, where you can fly home from there.
Another option would be to go to Munich instead, where you could visit Dachau, which is only 30 minutes from the city by train, and also some of the charming towns around Munich and Bavaria; maybe even Salzburg, which is close to Munich.
So there are lots of options, but I just think you're trying to do too much in too short a period of time.