How to determine if my guinea pig is pregnant?

Question
About a month ago we got two guinea pigs and thought they were both female. Until recently we found out that one was male and the other was a female. Lately they have jumping around, making funny noises, sniffing each other (like dogs do), and right after they do these things the male has been humping the female. This has gone on for about a little over a week. The female has been eating and drinking a lot more than usual. I am not sure if my guinea pig is pregnant and I have no idea how to tell if she is. Can you please help!  

Answer
She is most likely pregnant, drinking more water and eating more are the first signs. You really can't tell though until the female starts showing, which will be about 2 weeks after she got pregnant, sometimes later depending on how many babies she has. With how they are still acting would say that she is just now getting pregnant, females go into heat every 15-17 days, so she may have not gotten pregnant on her 1st heat cycle. Typically the male will calm down some once the female is pregnant, and the female will act more aggressive to the male. Gestation period is 68 days, that is when all of my females have their babies, some will also go to the 69th. The babies will start moving 4 weeks before they are due to be born, so once you feel them more count 4 weeks ahead. The male should be separated from the female at least 3-4 weeks before she is due, so in other words once the babies start moving go ahead and take the male out. You should be able to feel the babies in another 2 weeks, her belly should also get bigger if she is pregnant. Let me know if you have any more questions.
Brittany