Just take the cough syrup that the GP prescribed rather than suffering for such a long time - will not be good for your lungs and compromised immunity for too long is unhealthy for baby. If you tell GP you’re pregnant they will prescribe a preg safe cough syrup for you. I’m recovering from a covid cough now and all my medicines are preg safe.
Try Prospan Cough Syrup. Took it before/after pregnancy. Not too strong and safe. I will also put on vicks on my throat, chest and ribs area. Warm water, first morning gargle salt with water.