Help in looking for RA job in stem cell/regenerative medicine field!

[Salamandra7]

Hi,  Let me explain my current situation:

• I'm from the US, but I studied medicine in Mexico (gradated 2014). 
• I did a Master's in clinical research at UCSD (graduated Fall 2019).
• I have been working as a physician/surgical assistant at a vascular clinic in Mexico since my graduation form medical school.
• I plan to pivot my career into basic research/academia (I fell in love with regenerative medicine/stem cell biology while at UCSD).
• My goal is to pursue PhD in  the area of regenerative medicine/stem cell biology, in the near future.

My only research experience comes from my Master's thesis which was a project along the lines of health policy (unpublished). My work experience is mostly clinical, so I realize I need to build my CV in terms of research and skills in a wet lab in order to apply for a PhD in a competitive program, and so I'm looking to take a Research assistant/technician job as soon as possible. I'm willing to commit a couple of years and I honestly don't care much about being paid little as I know I have to take an entry level job, but I would require money to pay for rent/food etc.
Currently I'm living in western Massachusetts which is where some of my support system is (the rest is in southern California).  I am writing to several different labs in the Boston area (sending CV, 3 LORs, and SOP) and looking at job websites (Indeed, Glassdoor, etc), but haven't had any positive responses yet.

So I guess my questions are: Am I writing at a bad time of the year for this type of job (too early/too late)? Can it be something else that I've overlooked? What can I do to secure a job that lets me develop so I can reach my goal?

Any opinions, criticism, or tips would be very helpful! 
Thanks.