I had a rescue awhile back that I was positive was pregnant. Had the round-feeling stomach, elongated nipples, everything. I've bred for years and believe me when I say, I was positive she was pregnant when I got her. But... she never delivered. The stomach deflated, nipples shrunk now to a normal (non-pregnant size), and she settled down to a weight about 150 grams lighter. There was never any evidence of the abortion/miscarriage, or anything like that, just the weight drop and the pregnancy evidence went away.
If she was going to deliver, there should definitely be some weight gain, especially considering her latest delivery date would be later this month. Even with food switches, I've still seen a weight gain when a chin is pregnant.
If the fluid doesn't smell, I believe it can just be that she's in heat. However, I haven't had the experience to deal with any of the uterine infections, so hopefully someone else can come along and let you know for sure.