Kinda wonder if she ended up like that because she's a single mom.
Yes and no. In Chapter 14, we get her backstory. Growing up her Dad was very strict, she ran away and eloped, she argued with her Husband that he was too relaxed as a parent, his unit got transferred and they divorced.
She was always strict like her dad, but her husband was able to temper it. When he left, she became more strict. So in a way, it's because she's a single mom. But also, it's because of generational trauma.