baby not feeding

Hello, I have some questions if possible someone to help me please. This girl look happy,healthy and active at 23 weeks old,but I do worry because since she was 3 mo she refuses the breast if being aware that the breast is close to her. She would have then cry and push me away. I feed her only when she is half asleep or she is extremely hungry. For this reason,I started to give her some purées which she likes,but we are not on a strictly routine yet. I tried expressing my milk in a bottle and the thing is that she would only drink maybe twice a day from it and only 80 mls maximum then she is fussy and refuse it. She can go with no food about 8 hours. I also tried formula,but since birth she has projectije vomiting if I give it to her. I tried all sorts of formula and the same she vomits and does not accept it. What can I do? Why is this happening? She eats very little during the day and now even during the night she starts  to cry sometimes if I attempt to feed her. Help... I feel like she is not putting on weight and from nappy size 4 we went down to size 3. I am so so worried ... any tips are more than welcome. Thank you a lot!