In the UK if your MSc (or equivalent) is particularly good in terms of grades, or you simply enquire, there is the possibility of counting the MSc as 'Year 1' of PhD. However, this would mean paying MSc fees for a year of PhD. PhDs are generally cheaper on a yearly basis. It also means that if you do decide on this path, and drop out of PhD, you may 'lose it all'. - I was offered progression to 2nd year PhD from my MSc programme and eventually declined, I wanted more letters! No, I just wanted to be careful really.

I think what you felt when you were in your last programme is something a lot of us feel at various points. I started my PhD two months ago at the same institution I did both my undergraduate and master's degrees at. The experience couldn't have been more different - I felt lonely, isolated, somehow 'foreign' (like I did not fit) and entirely lost. To be honest, I still feel that way a good 40% of the time, but reminding myself of my goals and why I am there helps.

Overall, your personal happiness should come first. If you are unhappy with your research, think of ways to improve that - even small things help. Come here for advice - try not to read too many horror stories and instead read success stories. Be kind to yourself and try not to feel suffocated by the world of academia.

I hope you succeed in what you want to do! I very much sympathise!