Fasting at the Beginning of Pregnancy with General Malaise and Nausea

Hello and thank you. I am in the second month of pregnancy and feel a lot of nausea and general malaise. A few weeks ago, I had a check-up due to these feelings and was told that everything is fine with the fetus. Since then, I haven't checked, and I have an appointment only after Tisha B'Av. How can I fast? Thank you.

Shalom and blessings 

The law is the same as for any pregnant woman who needs to fast. If you feel strong nausea or vomiting, eat and drink as usual

We will copy from the recorded messages on the Beit HaHoraa line, extension 496:
A pregnant woman - if the pregnancy is normal and she feels well, she should fast, and prepare herself two days before the fast by drinking three or four liters of sweetened liquid.
If during the fast she begins to feel contractions [even if they are not real contractions but cramps], or feels strong nausea or vomiting, or headaches or dizziness or weakness – in all these cases she should stop the fast and eat and drink as usual.
However, there are many cases where a pregnant woman should not start the fast at all, and these are:
if the hemoglobin is below ten, or there were early contractions, even false contractions, or there were significant bleedings during the pregnancy, or gestational diabetes, even if it is balanced, or placenta previa, or placental abruption, or she is pregnant with twins, or there were miscarriages in the past, or she has a blood clotting problem, and also any pregnancy that is not normal, all these should not fast at all.

This year, when the fast begins on Saturday night, a sick person who eats on the fast must make Havdalah on the cup before eating [even a person who became ill on Tisha B'Av itself and needs to eat must make Havdalah on the cup]. If healthy people who are fasting hear Havdalah from him, they fulfill their obligation.
A woman who eats by permission on Tisha B'Av should make Havdalah and drink the cup herself [and there is no concern in this], and some say that her husband or another can make Havdalah for her, and she will drink the cup, and even the one making Havdalah fulfills his obligation with this.
If she cannot drink the Havdalah cup, she should make Havdalah and give it to a child who has reached the age of education [age 5-6] to drink the cup. If there is no child - she can eat before Havdalah and hear Havdalah after the fast.
The text of Havdalah for those making Havdalah on the fast: do not say the verses before the Havdalah blessing "Behold God etc.", but start with the blessing "Borei Pri Hagafen", and afterwards the blessing "Hamavdil Bein Kodesh Lechol". Do not bless on the spices [and if he has not yet blessed "Borei Meorei Ha'esh" he should bless in Havdalah, and if he has already blessed on the candle – he should not bless in Havdalah].
Those making Havdalah on the fast should preferably make Havdalah on grape juice [and even a woman making Havdalah drinks the grape juice as mentioned above].
The one making Havdalah should drink a revi'it from the cup (and although a cheekful is sufficient, since ideally one should drink a revi'it to avoid doubt regarding the final blessing, it is permitted for a sick person to drink all that is necessary for the final blessing).
The one who drinks water by permission on Tisha B'Av and does not eat - does not need to make Havdalah before drinking.