New Aquarium Are My Cherry Barbs Pregnant?

She could be carrying eggs or she could have stuffed herself at feeding time. Fish stomachs can look an appalling shape if they've over eaten. Check her just before the next feed and if she still looks like that, it's more likely to be eggs.
With both males and females in the tank they could spawn. Cherry barbs are egg scatterers, which means the female will release eggs, the male will fertilise them then they'll swim off and leave the eggs to fend for themselves. Most will be eaten, though there is a slight chance some will hatch, then the fry will be eaten. It is unusual to get eggs or fry surviving long in a tank with fish. Egg scatterers often spawn in plants, and if the plants are thick enough they'll provide some protection for the eggs.

If you want to breed egg scattering fish it normally requires a separate tank; the parents are conditioned separately, then the chosen fish placed in the breeding tank and removed as soon as the eggs are laid.