The less time you have for studing (because you are working, you've got a family and you are living the busiest time ever!), the more doubts you have about your level of "English reliability".
I am thinking of my experience: I didn't have the possibility of studing English full time, and when I started learning it, I was already working as a full time teacher. It's not the best condition you could face, but, if I did succeed, I stronlgly believe you can do the same!
In any case, if you are still doubtful, a good idea could be starting with a test about your A2 competence concerning grammar and vocabulary.
You could face two different situations:
- you don't have any problems neither with grammar nor with vocabulary. That's a good starting point for concentrating just on B1 preparation, and stopping you from having doubts;
- you are not satisfied with the results, and you are aware of some gaps in your previous preparation (it's not your fault, but you couldn't find enough time for English), that's not to bad! If you need a refreshment about your A2 English, you can go through the Reach your A2 blog and maybe find some useful materials.
In any case remember: never give up English!! :)