When should I start to worry?

Our calico, Ally, adopted us on May 28th. We are pretty sure that is when she got pregnant so that would be 9 weeks yesterday (Wednesday, July 30). She is huge but is showing no real signs of being close to having the babies. Her nipples are getting darker and every once in a while, you can see one move- there'll be a big bulge sticking out further on one side and I rub her side and it will move back in. I'm starting to get worried something is wrong, it's been 64 days now. At what point should I worry that she is carrying too long?  We're pretty sure she's got some Siamese or sphynx in her- I can really see the siamese in her head and face- and I've been reading some things that say that it's normal for Siamese to go longer than other breeds. Does that sound correct? I'm not familiar at all with pregnant cats. I've had cats all my life but have always had them spayed or neutered as soon as they were old enough. This whole baby business is making me nervous I'm ready to be a "grandma" LOL

I have heard this about siameses me too.  While other tell this is a rubbish tale.

Anyway,  cats seems to manage a little too long pregnacies better than humans.   But a short pregnacie much worse than humans - esp the premature kittens  arent safe.

Letts hope for the best!

She just can't get comfortable