I am currently 6 months into my PhD project as part of a DTP programme which means I still have around 3 years of studying left. I have really lost all of my enthusiasm and enjoyment for the project recently and I am not enjoying the working environment within the research group I am a part of. I have had lots of people notice how unhappy I have been and have suggested I consider switching to something totally new and start afresh. I have been offered a new project with a different PI I get along with really well and have only heard good things about from those who currently work with him. I've also spoken with my two current supervisors but I am not sure they really see how unhappy I am as they try and tell me everything will be okay etc. They have told me we can make changes to the project etc and see if that makes a difference and reassess in 2 months time. But I don't know if that is what I want or if starting new would be better for me. This decision has really been getting me down lately as my supervisors have been really supportive of me and I feel so bad that I am feeling this way about the project but I just have a feeling that it is not working. Other people have also warned me before that they did not think this project would work so maybe it is for the best that I change? Now would be the best time to do it as we are currently moving the lab to a new building so no lab work is taking place for at least a month meaning I can catch up on learning about a new topic etc. Any thoughts or advice would be greatly appreciated. Thanks!

Go for it as soon as possible. I have neglected the signs that my project is not suitable for a PhD and there were no prospects. It ended spending five years and exiting with nothing. If you are unhappy and the project and environment are bad, you have to leave immediately. Do not feel sorry for supervisor. He/she will not be affected.

I was in similar position to you a few years back and my supervisor at the time tried to reassure me everything would be fine and she would change but it felt passed the point where it could return to being good. Is there anyone thats not your supervisors you can talk to for impartial advise? For example by DTP had a course lead we could speak to. I went and spoke to them and ended up changing projects to ironically their lab but they did offer me other choices. I went from being unhappy to being really happy and no major regrets there. Trust your gut, PhDs are hard at the best of times but they are even worse if you are in a research environment you don't like, you need to know you have your supervisor and your colleagues to be there for you when times are tough. So my advise is change labs, don't look back and don't feel bad about. Do it ASAP if you are going to do, best of luck.