Essential Oils while pregnant

Ch
I have not been sleeping. It takes me hours to fall asleep, and once I finally do, I wake up several times a night either because I'm too hot or because my boobs are aching SO bad.
I thought about getting a diffuser and a lavender blend oil to help me sleep.
Is it safe to use?
Also - any tips for keeping my boobs from hurting so bad? I sleep with a sports bra, but every time I change positions, the pain is just unreal. They don't hurt that much during the day,  but nighttime is a different story.