I totally get the "you have to pay the bills while you're chasing your dream" concept, but going into medicine when it's not your desired career is insane! It's like one of the most expensive careers to get into, right? Granted, maybe it's not so bad in Japan, cause they have a lot of public education funding I think, but it's also still a huge time commitment. How long did she spend becoming a surgeon? The only way it makes sense to me is if she only realised she wants to do manga either after becoming a surgeon or on her way to becoming one, or she was pushed into becoming a surgeon by her parents.
Or, alternatively, she's a side character and the author hasn't put any thought into it besides "haha funy, surgeon wants to be mangaka, big gap moe"