So far, I was using my Android phone to shoot pictures and some basic point and click cameras. I would say that I am a low intermediate camera user. I know the basics about focus, depth of field, aperture, shutter speed iso etc. and I have played with different options. 

This year I decided to upgrade and bought a Sony A6100 kit with SELP-16-50mm lens. I realized that it is "too weak" to shoot in low light (my home) and bought also Sigma 30mm f1.4 (aps-c) prime lens.

My main need is to take family photos, mostly of my children. And this equipment is great when there is enough light. But now I have come to a dead-end and need to find a way to fill a shooting scene with light when necessary. The built-in flash on my camera is too strong for portraits (or I don't know how to use it), I usually bounce it off walls, but it is very awkward to hold it in that position while shooting (it is not intended to be used for bouncing).

My question is: does it make sense to buy Speedlight? Will it cover most everyday situations where I would need to shoot children photos (birthdays, portraits, children playing etc.) or would you recommend some other solutions for me? I am not looking to set up a home studio, so heavy equipment is not my thing but something light and versatile will be perfect. Which one would you recommend? Is there some best buy option where intensity of light can be adjusted? 

Also, a recommendation for a beginner tutorial on how to use it would be great.