Another update:

So it turns out she's down 300g in weight. I haven't been able to use my scale since it's been broken and I just got a new one. She dropped that weight in two months.

I'm going to talk to my vet on Monday and see if she can see my snake or at least prescribe an appropriate dose of flagyl to help stimulate her appetite, and if she has worms or a bacterial issue, this will get rid of it. If there is nothing.. well at least it will stimulate her appetite!

My other option is the vitamin B 12 shot, which I believe is available over the counter. I don't know dosage on this, and am a liiiittle more iffy because of that. I'm leaning towards flagyl. I'm not bothered by injections or oral meds, as I've done it with many a cat and dog... but any tips on how to do it with a snake would be greatly appreciated. :]

Thanks everyone for their help and input. <3 I want my girly to be happy. She's the most gorgeous pastel I've seen at her weight and she deserves to feel good and eat!