What the hell do i do with a 7 week old kitten

Haihai! Jam here! Recently life has been full of surprises and twists and turns which throws me off completely. 

Earlier today whilst at college, my mom texts me with a picture of a stray kitten in my sisters hands. Looks very small and the following messages states "we have a new member of our family! we found her near a Chase Bank with other kittens. We tried catching the mom so we can also grab the other kittens and take them to the shelter but unfortunately she's very skittish but we got this kitten!" Now many emotions ran through me, of course I was overcome by joy since I love animals and I like helping them out the best way that I can. Than it hit me, we already have two 4 year old cats that are both male short hairs. To be honest with everyone here, my mom cannot financially support another cat especially she can barely support the two cats we have and even her own kids (me and my sister). Of course I turn to my bf cause im worried about this new kitten cause I know kittens need specific things to live and certain vet check ups ESPECIALLY IF ITS A STRAY. So as any animal lover would do, I start researching what a 1 month old kitten needs to survive especially if its being domesticated. From researching we would need KRM, kitten replacement milk instead of regular cow milk BECAUSE cow milk does cause digestive issues including diarrhea. THIS ISN'T GOOD EVEN FOR A KITTEN BECAUSE it can cause huge problems and even death if it doesn't get the correct nutrients. Next, we would need a heat pad that is turned on Low and ofc comfy blanket so it keeps warm cause kittens can die from being cold. Now, right now in Florida specifically in Miami, its 69 and getting lower which we are expected to hit the 40s the following morning. Of course the kitten is in the house, in a cage with some blankets and a makeshift sweater made out of a thick sock. Now what's pissing me off is that my mom thinks she knows what she's doing which yes I understand she has had cats before but also GIVING KITTENS COW MILK IS NOT GOOD. especially that idk when it has eaten or has it eaten at all. And I hate how obsessive my sister and mom are over the kitten when tbh it needs proper care or it will die. To be honest in my honest opinion, I don't think my mom and sister should own this kitten mostly because my sister doesn't know how to take care of shit, especially she has two iguanas that she treats horrid. (btw she is 17 but does have a learning disorder and autism which was hella ignored by my mom cause my mom is an idiot tbh.) I honestly think I can take care of the kitten but tbh I barely have money or make money for myself and usually depend on allowances. I would consider getting a job ONLY because the kitten would be my responsibility. Ofc when I got home my mom automatically assumed i bought food for the kitten when I had to buy new shoes, plus get food for me and my bf since we didn't eat all day. So no unfortunately, I couldn't afford or even go to a supermarket/pet store for the kitten. Tbh I will say I feel like the kitten would be better off if she went to an adoption/shelter but also I've grown attached and do want the best for this kitten. 

If anyone can give me advice what I can do for this kitten, that would be amazing. Im a 19 year old college student who currently only makes money by doing art commissions. but also gets allowance. But idk how much vets would be, or even like food, etc. 

Jam out.