If you are in Canada you can go to any walk-in clinic and get advice from the doctor there. I'm not sure how it is in a lot of other countries, but in many places in Canada it can take a week to a month to schedule an appt with your family doctor because of massive shortages. Go to the walk-in, be honest (about using marihuana) and they will guide you from there.
Now, I'm not going to get up on you about using marihuana when pregnant, just give you some basic information. A lot of marihuana (in fact most) sold in Canada is no longer pure marihuana and the THC content is extremely strong, even much moreso than in the US. A lot of marihuana sold is laced with various other things, like cocaine, meth, and heroin. Sounds nuts, but yes, this is very true. So you have to stop.