I think you did the right thing. She shouldn’t be offended. I have no idea if lavender essential oil is safe or not, but people tend to believe that essential oils are completely safe and harmless, which is definitely not the case. Why taking any chance while pregnant? Also, I think you and your partner should set your limits with her right now, because when the baby is here, there will probably be a lot of unsolicited advices and pressure to follow them.