Hey
I'm not entirely sure about this but I think if you switch from BTech to Eng, you will be placed in Year 1 Eng. The reason is that the courses are not similar, some are outright on different paths. Again, I'm not entirely sure.
Going the other would be a lot easier since you could transfer credits.
Another route you can consider will be getting your BTech BA and doing some PEO exams to become an engineer.
To be specific I'd speak to a academic counsellor, either Sally Williams or Arlene Dosen I believe. They would be able to shed some light.
Good luck next year!