I am sorry to hear that your semester ended this way. Where I work, there are skills tests at the very end of the semester, but these are re-tests, for those wh have failed it. They need to pass it at the end, which (in our case) was the day after the final exam. If they do not pass the retest, they fail the entire class. This is the first semester for these students, they need to pass lecture, clinical and skills.
In the other place I work, the students were tested only on one skill (in their second semester). They were tested the first week (learned the skill the previous semester), retested sometime around October, and then retested (if needed again) at the end. Two of my students needed the third try, and I do not even know if they passed, because they waited to be retested until after clinicals were done. So for all I know, they could have failed the entire thing.
I know it stinks, but I'm guessing the theory is, you have had the entire semester to learn and practice the skill(s). As someone who is on 'the other side', you may hear this (in some way), that you have had plenty of time, and it is your responsibility to practice the skills on your own. I am just playing devils' advocate. As an instructor, I can't tell you how many students I see standing there after I have introduced the skill, and when it is time for them to try it, they either take a step back, or head for the door (there are many who do not too, so yes, I am generalising). And when they get to the hospital they are all thumbs, because they have not physically practiced the skill. I know this may not make you feel any better right now, but I am just preparing you for what you may hear.
And of course, I cannot comment on the double lumen catheter that you never saw. That would definitely be something that you could bring up, as you should be well informed of the things you should be tested on.