Why do you find yourself without instructions?
- Are the assignments being explained to you? Do you repeat the task back to the delegate to ensure you know what you're supposed to do?
- Do you ask for help when you become stuck? Do you get answers back from the delegate?
- Do you complete the task and turn it in when it's less than perfect? Do you get feedback on how to improve?
- Do your seniors know where you struggle and what you struggle with?
If you do all of the above and get no feedback, I'd suggest doing projects on the side to sharpen your skills. Try to learn new things that would be valuable within your job.
I'd also look outside your current supervisor for a mentor that could help you when you get stuck. It would be useful to at least know where to look for answers.
If you can turn in sub-par work and get no feedback, then there's also an issue with your current supervisor or the work isn't sub-par. If that's the case, that's something you should bring up with the trainer.
Additionally, this may be more appropriate for the workplace SE to see if anyone has asked about it before or if anyone has some advice for how to approach the trainer, as that's not my expertise.