I would take her to dinner and have a heart to heart before giving money. As others have said before, you can offer to pay bills or help in other ways but flat out giving cash sounds like a recipe for further poor decision making.
She's lucky that she has someone like you that cares, @what. Sounds like she's up against it being 18 with a 3 year old kid, and a boyfriend that doesn't deserve her. I noticed that you said she'd just gotten her vet assistant certificate. That's not a very high paying job. If she could get an associates degree (not sure if it requires a particular program - maybe, probably - so what?), she could become a veterinarian tech. That actually pays a decent salary for an 18-20 year old. Twice, at least, what a vet assistant gets. The average is about 32K. Maybe you should take her out to eat without the boyfriend and talk to her about getting a couple of years of college, that associate degree, and becoming a vet tech. Get her excited about something. Does her family help with baby sitting? Would they be willing to look after the kid if she went to night school while working as a vet assistant? Just a thought. She needs to lose the boyfriend. Maybe if she got serious about school, he'd get the message.
That may be what she has, she took a test after high school and passed. She was also planning to go to college for veterinarian, last I heard, I'm not clear on everything, but yes she does plan on having a career in animal care of some kind. She has a lot of support if she wants it. The dude is nearly 10 years older than she is: she can't handle him, being so young. But again, she is 18 and rebelling I assume.
Good of you to intervene. 18 ... she still has her whole life ahead of her. As some have stated, try being her life coach. Take a look at her bills together. Find ways to cut spending and generate a plan for the future. Dont keep feeding her that money without some direction. It's understandable you trust her but it's also naive to trust her. The boyfriends sketchy and substance abuses cant be ruled out. But it's a tough situation and only you can truly determine the best route to go here. Good luck. Hope it all works out.