Should I change thesis topic?
This is certainly a question you need to explore with your supervisor. What they would accept or recommend is certainly important. 

What an experienced researcher would do is one of the following, maybe both. First, they would be likely to consult with colleagues (not unlike your supervisor) and explore viable alternatives. 

But, assuming that they have a secure appointment, such as tenure, they would do whatever most appealed to them. Of course, wisdom would suggest they keep their options open. 

But you don't have the luxury of a secure appointment. Your supervisor's advice is needed and should probably be followed. They will also have advice on the probably effect on your career, if any. 



Actually, I think you may be suffering from a common ailment: Buyer's Remorse. For most such situations, the feeling of regret goes away in time. If you are making progress toward a better future, you are probably doing the right thing. Don't let emotions get in the way of progress (easy to say, of course).