The volume a 3 month old drinks and sleep training

Hi mummies, my LO is almost 3months old and she can only stomach a maximum of 120ml (rarely and might vomit). Her average volume consumed is 90-100ml. She takes formula milk. She can sleep well at night and we dream feed her which may take a long time and it’s killing me because I really need longer stretches of sleep 😥 So, I want to sleep train her but if we don’t feed her every 3 hours, she will consume very little and I’m afraid she won’t get enough nutrients. My questions are 1) how much does your LO drink at 3 months old? Each feed/whole day? 2) any one with similar experiences and how did you overcome it? I really hoped to start sleep training her before I start work but it doesn’t seem feasible if I want her to drink sufficiently.