I think Ma was really doing her best. She was so young when taken, that I think she still has a lot of growing up and learning to do. But she really did her best in a chronic situation.
Jack was deprived of so much social interaction. He didn't understand that he what he saw on television could be real.
But Ma did a brilliant job of teaching him how to read and write. She also had a lot of structure in their day. The fact that they had a fixed time to eat, to exercise and to learn was very important.
Ma would have been trapped in a never ending cycle of abuse, pregnancy, abuse etc. Although the abuse went on, Ma protected Jack from it by placing his bed in wardrobe.
Ma did the right thing by not telling Jack about outside before she had her escape plan ready. It was a shock to Jack's system but Jack is young and with help, will cope.
At first his biggest challenge seemed to be stairs. He wend down them on his bum for a while because everything in Room was the same level. I think his biggest adjustment would be all the people. After just being Jack and Ma for all of his life, to suddenly have so many different people all coming and going, but yet the only constant was Ma. The difficulty is hinted at when Grandma says that Jack is very difficult and she's at the end of her tether. In my opinion it shows that Jack is finding it touch being around strangers.