Why can't I do a push up?

Hey everyone,

I've been working out for about 6 months now & I workout like 6x a week with a combo of strength, HIIT, etc., however I can't seem to do a push-up! It's not like I don't have any upper body strength because as I've mentioned that I do weights & I'd say that I've fair upper body strength but I just can't seem to go fully down with my chest, even when I'm trying to do a push-up on my knees let alone on my toes lol. The only way I'm able to go fully down with my chest is when my hips are up, but I know that isn't the correct form. Is anyone in the same boat as me? Am I doing something wrong? I really wanna be able to do a push-up :(

I look forward to your replies.