I hate that my boobs are succumbing to gravity

My size pre-pregnancy was around 36C (although lately I've just been stuffing them into a too-small sports bra) and every time I look at them I feel like my nipples are gradually pointing more and more to the floor. I'm 18 weeks. I've done some degree of research on breast ptosis (sagging) but if seems like you can't do shit about it other than surgery. Anyone been able to really lift things up with exercise or something? I really don't want two big sausages laying on my stomach with nipples pointing due south.