She probably had a lot of friends at school, maybe even been given extra care by teachers, and was only alone at home. She doesn't seem to have signs of intentional abuse or neglect, and what little of the house we've seen in that flashback in chapter 1 was clean and tidy, so it was probably just her parents needing to work long hours.
Ultimately, we just don't have enough information yet as to what her life was like before she isekai'd. Just that she was alone enough at home to learn to cook for herself, and that she had a good enough relation with the adults in her life to readily rely on the guy who found her without a hint of fear or doubt that he would help. Hell, she didn't even have the "stranger danger" response.