confused...

Hello, my mom was diagnosed in September with metastatic cancer -- ovarian to peritoneal.  She was not a candidate for surgery and had one round of chemo, following that the oncologist advised that given her weakened state the option to pursue was palliative management, therefore, no further chemo treatments following the first one.  She is currently living with me and my family.  She had a PleurEx catheter inserted for home drain of ascites.   Here is the confusing part for my family.  Previously, the fluid was building up every 24-48 hours causing pain and discomfort, with this permanent drain the fluid isn't building up nearly as quickly (I suppose that means this treatment method of keeping comfortable is working), however, in a call with the oncologist last week, he told her she had weeks to a couple months remaining, but...in 2 months we have never seen her feel better...her appetite is fantastic, her mobility is better in terms of walking around, she isn't napping nearly as much, so we are confused....how is her current condition indicative of 2 months left???  Are there any similar experiences?  Is this the calm before the storm?