I am a student in US studying engineering. I know that we should not work for military or help in it, but for some class assignments i have to do discussions w other students. idk if they plan on working in military or not, but i fear participating counts as helping them if they do. is this waswas?

Dismiss these thoughts as mere speculation. We don't forbid something lawful today just because someone might do something forbidden tomorrow, like potentially working at an alcohol company. Without proof, basing rulings on hypotheticals means everything would become forbidden, since anyone could potentially do something wrong in the future.