22lbs isn't too far off really, my little girl was just over 24lbs at 2 years old.
I was always worried about her weight but professionals never seemed bothered, they just said she was petite although she was quite tall. It started mainly with her when she caught pneumonia when she was 2 and she lost lots of weight. She ha always been on catch up ever since. She hadn't eaten properly for over a month and lost so much weight. We managed it through monitoring her food intake and she has gradually caught up. He doctor said to not restrict anything, if it's fatty etc and she wants it, let her have it! He said too many parents are restricting fats for children as they are scared of them becoming obese, he said this has caused so many problems in recent years with the children he has seen. Young children need full fat milk, cream, cheese etc nothing with reduced fat. Aim for 3 meals and 2 snacks a day if you can. As much variety as you can get into her. A good breakfast is really important, healthy cereal - Grace use to have two or three weetabix with full fat milk with a cup of milk to drink too. Mid morning she would prob have some toast with butter or a yoghurt or both, poss some fruit. Then at lunch she would eat a tuna sandwich or beans on toast, add a bit of grated cheese for extra calories. Same with dinner, spag Bol with extra cheese on top or something like that to give that extra boost. If she wants desert let her have it. Depending on what time she eats her dinner you may be able to sneak in supper before bed, with Grace that would be a small bowl of weetabix again or a toasted teacake or something.
My HV said that we could get her on some weight gain type drinks around her meals to help put the little extra on if he became ill like that again and lost weight. Just a short term thing but apparently it gets them back to where they were before hand, so maybe thats an option. I can't remember what they are called but they are specifically made to help children put on more weight after illness or to give them a boost. Your GP could help, I think they are like milkshake type drinks. She never needed it luckily.
I also started Grace on multivitamin liquid tonic to help give her a boost too. Xxx