Rushing ahead

I am very annoyed at my sitation right now because I ended up spending a full day working on the pattern block for my tunic, for me to then find out that I had made a crucial mistake at the very beginning. This then had a knock on effect when I stared to draft the sleeve, it was at this point when I knew that something wasnt quite right as the sleeve head was way too wide and short. I then ended up spending a substantial amount of time trying to suss out the error, which eventually appeared at the first instruction to add 4.5cm to the scye depth, which I did not do.
I think I am more annoyed about the fact that my time is very limited as it is and I dont want to be making silly little errors which I shouldn't really be making in the first place as a third year student. I am annoyed at myself for rushing ahead and not reading over the instructions more carefully. This could have been avoided, and the lesson learnt here is it is always better to read things twice as the mistakes that you make can effect your process later down the line. In regards to the style of costume that I am making, because of military uniforms being so precisely made not to mention the price of the material being rediculously expensive I cant really afford to make these sort of mistakes. I have decided to start again tomorrow, and I will make sure to take my time with the new pattern as well as with all the other parts of the process.