I had the same problem just a few years ago.
I decided to go flight training as apposed to another year in uni and definitely do not regret the decision. I felt there was no point in sacrificing another year in order to be slightly more qualified for a job I did not want to do.
If you want to fly then go and do it, you can always go back and do a masters. I see little point in gaining more debt in student loans etc. If flying is what you really want, you won't need to worry about engineering again because if you are determined enough you will be successful. Also I believe it would not be a bad time to begin flight training.
Just my opinion, hope it helps and best of luck with whatever decision you come to.