I calmed down last night, eventually and decided to cut some more patterns and to really take my time. I think I was not taking enough time, with measurements and accuracy with my patterns and setting the seam allowance. So, things just wouldn't line up.
I also learnt, that when a curve lines up to a straight line they are not they same lengths !!! Seems obvious, but I was ignoring a very slight curve, which makes a huge difference when you pull it all together. See the shoulders on my chair !!
I think, I've got it now. So, back to the machine. I'm loving it. I also made a carpet set for the car with binding and that looks pretty good and a perforated headlining, which I have fitted, which also looks great, so it's not all frustration !!