Im under chronic stress all the time, i am 18 years old. and have a lot of issues. does this mean that my iq will be dropping?

Not permanently: High stress can impair memory & concentration so you might perform less well on an iq test taken when stressed, but it should not permanently impair your intelligence. It is important to take steps to manage your stress, like exercise, adequate sleep, meditation, counseling & healthy diet. Supplements can help too, esp. B complex, vit c, magnesium, ashwagandha, rhodiola & cordyceps. Good luck!