It depends on each animal. For example, I bred a 1400g female that´s all muscle and is young, but I have another female that´s been with me for 4 months only, she was weighting 1400g but was way underweight, she has the same head and length as a 3500g female. She´s now 2000g but you can tell she´s still underweight, so she probably has few or none fat reserves that are necessary for breeding. I´m not breeding her until next year. Losing 400g IMO is a lot, she´s supossed to start eating when growing follicles, maybe you can wait a little.