I had similar problems with my new glasses. I couldn't focus correctly with my right eye (blurry).
I started off with new thin lens but could not adjust to these no matter what I did. Got these changed to standard single vision lens with anti-glare coating which helped ever so slightly - just. Again got the lens changed at my expense but the same problem was still there. I was beginning to think it was just me and that I was imagining it.
I left it for a month and then went to another opticians on the high street. Paid for another eye test just to put my mind at rest (second opinion). The change in my prescription was ever so slightly different. I then picked another frame as the optician said the new frames I had were too big for my face shape. So frame choice is crucial.
I was sick of the sight (no pun intended) of my other frames anyway because of the previous lens problems.
At last, I could now focus and see. The optician explained that it could have just been the lens make and manufacturer that solved the problems. She also mentioned that in some rare cases, it can take people about a month to adjust to new prescriptions. So it's not just you buffymad. Stick with it.
From this experience, I now know I can't wear thin lens or Pentax lens.
PS. When taking your eye test, ensure the mirror is directly in front of you and not offset to the left or right.