My son is a comp sci major, and his university is very clear that this type of sharing (providing previous work, copying code, etc.) can get you expelled. If I were you, I’d quit doing it. Just say no and don’t apologize.
Why are you okay with doing all the work for your team? That’s foolish and takes away from time you could spend doing other things. You should insist on their help, and if you don’t get any explain to your professors what you contributed and what they contributed.