Why can't I seem to save any money?

I'm a single woman approaching 60 years and now retired. I've tried to scrimp and save because I get less than $3000 a month in pension benefits. I really only try to spend money on groceries, property taxes and utilities. However, I've been keeping track of my net worth the past year or so and find I'm actually losing money. The main cause is plummeting interest rates on my investments. My goal (and somewhat of an obsession) is to be the first one in my family to become a millionaire, but this goal has proven elusive. Some months I gain a little and think I'm almost there, then I have an unforeseen expense. Last year I had to buy a new refrigerator, have extensive plumbing work done as well as more than the usual car repairs. It's like trying to catch an outgoing tide. What can I do?