@msong06 - you should be asking the question about BOTH your child and your girlfriend. If she lived with you ALL YEAR and does not work, you can claim her as well. Assuming you claim the baby, your filing status is HOH. Claiming both of them is worth UP TO $2500. I suspect you are eligible for EITC as well.
When was BABY born? depending on the answer you get to your Medi-CAL question, if Baby was born in 2022, I'd go back and amend that tax return.
I can'r imagine claiming your child and girlfriend affects your medi-cal coverage - these are federal credits and not income, but suggest calling and posting back the answer.
