And some instructors I know were given a 709 ride for essentially what you are detailing. I remember my first manager told me "your first few students kind of get a crappy deal", due to the relative inexperience you have at this point. It sucks that happened to your first couple students, in fact that kind of brings to light the entire issue of the least experienced pilots (brand new IPs) training new pilots, but that's another issue.

The FSDO and Inspectors are usually pretty understanding when it comes to this. Although you can't be 100% certain a student will pass, it is your responsibility to make sure they are trained, and if you determine that you can't train them past a point, don't put them up. The Inspector will know you've only put up 3 people for a checkride, so they are just looking for some basic skills, usually nothing fancy, and if you are a current pilot, it shouldn't be anything to worry about. Logistically it might be a pain, but look at their job, they are not out to "get" anyone for pleasure, they are out to ensure standards are upheld. They need to find out if this is just a "fluke" or a serious problem. I assure you the Inspector hopes it's a "fluke". They aren't your friend, but they are not your enemy either.

Then, you might want to read some of the information that is put out there on checkrides from DPEs and the FSDO (they do have some resources!). Sometimes for lack of a better way to put it, some flight schools and even DPEs don't really enforce the standards, letting people get away with things that won't pass or are contrary to how a check should be performed.