So, goats cycle roughly every 18-21 days. If he was in there a month, then ya she's probably bred. If he was in there 2 weeks... could be hit or miss. This is why it's so important to write down the date you put a buck and doe together, and the date you seperate them. Then your guessing gets narrowed down a whole bunch.

Even better is to hand breed (watch for signs of heat and watch the buck breed the doe), but that means you need to be around to witness it, and of course that's not always an option. I had to pen breed this year instead of hand breed.. hate it! But.. I didn't have another choice. At any rate, does are pregnant for approx 150 days, so if you count backwards to when you think they might have been together, you'll get a rough idea of when she might be due.. at least narrow it down some.
Udder development... all of my first fresheners (first timers) start making an udder several weeks in advance. Can it happen overnight? Yes, but not very often. That kind of "development" is usually reserved for does that have done it before and go from a flaccid udder to a full udder in no time flat.
Ligaments... feel the ligaments on the doe you believe is not bred (was she never in with the bucks? ) and then feel the ones on the doe you believe is getting close. Normally they feel similar to a pencil with a little give. As the doe gets closer to kidding, these begin to soften until they completely disappear and it feels like if you grabbed the tail head your fingers would almost meet underneath, Now it can take 1 day for this to happen or on one of my older does, her ligaments are gone for 2 weeks, lol.
Leading up to kidding your doe will paw at the ground.. we call this nesting. Their behavior will generally change some also. (some of the things you were describing earlier)
One of the last "signs" you will see right before kidding time is the doe "drops". She goes from carrying the babies kinda up high, to lower in her belly, getting them into position. When this happens, she'll go from looking fat to looking like she hasn't eaten in a week. The sides right in front of the hip bones get a bit hollowed out. When you see that, you know the babies are coming soon. (Some does it is more visible than others).