I made a similar transition at 35. Have you looked at quant developer roles? They may value your experience and background more and be more willing to compromise on your software engineering experience.
I did it when I was 36, but I wasn't a quant. It took a coding bootcamp to get to where you say you are, maybe a little bit further. But given what you say, you can skip that.
While you probably don't need a full year of self-teaching fundamental computer science to be able to do the job, or to interview, you may need to drill and kill algorithms problems on leetcode or similar.
While you probably don't need a full year of self-teaching fundamental computer science to be able to do the job, or to interview, you may need to drill and kill algorithms problems on leetcode or similar.