First Mistake? 50 Pack of Frozen Feeder Mice

[Eric Alan]

Related question - how "old" roughly is a female at roughly 150g?

Likely no older than just a few months. They hatch in the 50 to 100 gram range, so it doesn't take many meals at all to get up to 150 grams.

And how big (roughly) is a well fed female at roughly 1, 2, 3 years old?

That's much harder to say. I've had females by 1400+ grams by the time they were a year old and others that were around 600 grams when I got them at a year old. With that wide of a window, you can imagine that putting a weight range on a 2 to 3 year old is even more difficult. Healthy body proportions on a well-cared for animal is the most important thing.

I probably overdid it on a young snake enclosure when she is just going to pork out and need a new enclosure before I know it. (Excuse to get another youngin to fill the small cage?

You'll start out needing excuses like this to get more snakes. Those excuses gradually devolve into "because it's Thursday".

I should dial back the enthusiasm though, I don't even have a day of snake ownership under my belt.

NEVER dial back the enthusiasm!!!