Hi,
A cat's gestational period is an average of 63 days, so if you believe she got pregnant approximately 6(?) weeks ago, she might be ready to deliver in about 2 weeks or so, if she IS pregnant. In addition to her rounded belly, her nipples should be darker, more rosy in color, and there might be hairloss around them. Her appetite also should have increased.
The excess gas may be indicative of several conditions. She MAY be more gassy due to the pregnancy, if she's pregnant. She may have a uterine infection called pyometra, which can cause bloating of the abdomen, but she'd most likely also have a vaginal discharge and be acting quite sick. She could be experiencing a false pregnancy, and that's why her tummy looks more rounded; she may have a condition called FIP (feline infectious peritonitis), which is quite serious and also, she would most likely be acting sick, not wanting to eat, etc., or, she could have intestinal parasites, as these can cause gas and abdominal distension. Here is some additional information on some of these conditions:
http://www.sniksnak.com/cathealth/pyometra.html
http://www.sniksnak.com/cathealth/fip.html
http://www.sniksnak.com/cathealth/worms.html
http://www.sniksnak.com/cathealth/coccidiosis.html
http://www.sniksnak.com/cathealth/giardiasis.html
http://www.cat-pregnancy-report.com/cat-pregnancy-signs.html
She could have allergies to some ingredients in her food, if it contains corn, gluten and/or artificial preservatives.
http://www.sniksnak.com/cathealth/allergies.html
If she's pregnant, she should be eating a quality KITTEN food for extra calories and nutrition, and some good brands are Wellness, Felidae, Innova, available in major pet supply stores.
A vet visit at this time, would be a good idea, to determine if she's pregnant and also make sure she's in good health.
I hope everything works out well, and if she does have a litter, don't let her outside at all, and have her spayed 10 days after the kittens are fully weaned, at about 8 weeks of age.
Cher
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