Hey, you've worked for three years and that experience never goes to vain. Software testing and Data science are two very different domains, software testing experience might not help you very much to get a data science job plus a break adds up to your disadvantage.
Show the company that you've learned something that can be contributed to their company during the break and use to your advantage. Take up a certified course, there are many e-courses, you can just sit at home and study. Udemy, Coursera, Edureka, Udacity, IBM. Do some basic research, find out the best course suited for you and go for it. Once you have the certification, knowledge, and experience working with the tools nobody can't stop you.
All the best :)