I wouldn't recommend EO during pregnancy especially if you are totally new to EO, plus you are still quite early on in your pregnancy. Too many seemingly benign oil and oiling practices can be harmful. E.g. cinnamon and rosemary are not advisable during pregnancy. No point asking your gynae either as he/she is likely not trained or licensed in aromatherapy. Do take whatever a lay person tells you with a pinch of salt, they may not mean any harm but EOs can be harmful when not used properly. On a related note, pls build up you immunity throughout pregnancy. Eat well and on time, take your multi vits, get more Vit C e.g. redoxon, and hot lemon tea to relieve the congestion. However, if u are very sick, pls go and see your gynae rather than trying to self-treat it. Especially in light of the covid19 situation. The meds that your gynae will prescribe when you are pregnant and ill are tried and tested and won't harm the baby.
Try essential oil. But pls check with your gynae first! Some are unsuitable