I am currently an astrophysics student finishing my third year of my PhD. I attend a prestigious R1 institution in the USA and I have a very supportive advisor. I get along well with most of my cohort, fellow graduate students, and faculty and feel I have a decent social life.

However, I do not feel the research interests of my department are right for me. The astronomy research here is too observational and I prefer theoretical/computational work. The reason I accepted my current school was because

1. Out of the 3/17 astronomy PhD programs I was accepted to, this school had the most astronomy faculty, hence the most options.
2. The brand name of the school was the highest.
3. I wanted to go a different region of the USA than where I grew up.
4. I wanted my school to be in a big city with a diverse population so I could have the opportunity to meet people that come from different corners of the world.

I performed satisfactory with my classes and I loved being a TA in grad school. However, my research experience has been frustrating for me this whole time.

In my first year, I only considered one person to work with because he is a theorist and his field was somewhat related but still far from what I did in undergrad. I realized by the end of my first year that I did not have the passion to work in his field for my PhD. He ultimately did not have the funds to take on another student anyway.

The summer after my first year, I rushed my affiliation with my current advisor because the department affiliation deadline was the end of the first year. I ended up reading the review papers in their field for just 2 weeks and was like "Hmm, this is kinda interesting." They are also very nice and approachable and I was biased towards young, newer faculty, so that led to my affiliation.

Since then, research has been an incredible slog. I feel no passion towards my field and miss the original field I worked in my undergrad (I even read more literature of this field than in my current field because of my passion for it). I have no interest in participating in my group meetings, reading the literature (until my advisor pushes me to), and paying attention/asking questions in seminars because I simply have no passion for it.

I have no conference experience and I am realistically a ways off from publication status. I have 0 first author publications and only 1 co-author paper, which is from my undergrad.

I first thought this was burnout, but I have seen my therapist several times now and I take care of myself well in general (eating well, exercising, sleeping well, enjoying hobbies). My therapist and I agreed in therapy that there isn't depression going on here, but I may not be interested in my research field which leads to me procrastinating a lot on anything related to my project.

If I stay, I see the next couple years as a slog because of this research interest mismatch. Since no one at my school does research in the same field I did in undergrad which I am intensely passionate about, I was wondering how wise it is to leave with my master's, apply again to PhD programs, and work with people who work in my desired field? I know I would have to start over, but I feel I could progress faster if (1) I am passionate about my field in astronomy (2) my skills and past experience in undergrad are suited for the new project and (3) thanks to my current advisor, I feel I am a better at some research tasks now (lit review, setting up paper draft, problem solving, etc.) (4) I have an MS and can possibly transfer course credit and TA work.