I think I'm financially abusing my little brother

Obligatory on mobile, and throw away because my brother and I regularly share posts and interact on my main.

I (26F) live with my husband (28M) little brother (18m) and my daughter (1F), I am also 30 weeks pregnant. My parents got divorced and neither stayed in his school district, it's his final year of highschool and he has grants and plans to attend a local community college after he graduates. We all work, I work part time and husband and brother both work full time. My brother pitches in 600 a month for all bills and we cover the rest, now this is where I was told I am being financially abusive by my parents and his friends, he hasn't spoken up against our current arrangements himself. He pitches in that 600$ a month along with grocery money, and he also pitches in when we are short for anything, he saves money from every check for anything the grant doesn't cover during college but I've heard from his friends that he will actually pull money from his savings to help us out, he never told us and never asked us to pay it back, husband and I are both saving for our second child and don't dip into it for any reason. My brother gets paid one week and husband and I are paid the next, both bi-weekly pay, he uses my car since he doesn't have his own so I also make him pay for gas, meaning he is obligated to throw in on groceries, gas, and bills, not sure how much he spends on gas but he throws in about 300 on food, 600 on bills, and at least 200 on gas a month meaning he is paying 1100 to stay here and we have him spot us on stuff for the baby if I run out during the week hubby and I aren't getting paid. Writing this out I can see why they believe we are abusing him financially as he is trying to save for college and we already require him to pay us 1100 in living expenses a month. It's rare but we will spot him for any amount he asks for whenever we are paid, I feel like this is why he hasn't complained along with the fact he is hoping the grants will pay for all college expenses. I may add a bit of our baby fund to his college fund to help him. We have around 6,000 saved so I might add a months expenses to his savings or when he starts his semester of college tell him we will cover his living expenses for that month. This is more to write down the living arrangements we currently have and put down what I'm thinking about doing to fix the situation if I truly am abusing him financially. I'm open to suggestions and opinions.