Has anyone gotten pregnant on the cycle they started or used a cough syrup with Guaifenesin to conceive?

I don't think I've ever had EWCM, but I have had watery. So to help my CM along, I've read and been recommended by pregnant friends to take cough syrup. After doing some reading, I found out I only really need one with the expectorant Guaifenesin. I hit up my local pharmacy and the pharmacist recommended Robitussin.

I got a bottle of Robitussin and started taking it once a day. But now I'm reading online (like the Globe and Mail) and it says women take it up to thrice a day. How much did you take? Was it helpful?