The Couch Potato strategy is designed to deliver the same returns as the overall stock and bond markets, minus very small costs. Index funds and ETFs offer no protection from a falling market. The only thing they promise is that your gains or losses will not be significantly different from the indexes, and that you won’t be losing 2% or more each year in fees. The funds your advisor uses will sometimes lose less or gain more than the indexes. But over the long term this is unlikely to continue, because the drag caused by fees is relentless.
You mentioned that you got started with the Couch Potato strategy in mid-2007. Through no fault of your own, this turned out to be terrible timing. Stocks markets around the world saw huge gains between 2003 and 2006, and mid-2007 was the peak of that long bull market. So you had the bad luck of buying when prices were highest. Things immediately got worse in the second half of 2007, and then 2008-09 saw the worst crash since the Great Depression.
Just about everyone who had money in the markets—and your portfolio was 75% stocks—lost money during this period. The Canadian, US and international markets are still lower than they were in 2007, so the ETFs that track them are down, too.
You also asked whether you need more than $10,000 in the portfolio to make it worthwhile. In some ways, the answer is yes. Using ETFs and rebalancing once a year is inefficient with small accounts. Many discount brokerages charge $29 per trade, so the cost of rebalancing is about $116, or 1.16% annually on a $10,000 portfolio. Of the $950 you have lost in your portfolio, more than a third would have been from brokerage commissions if you have done three rebalances (12 trades at $29 = $348).
If you decide to stick with ETFs, you might consider rebalancing only every two years (or even less) to reduce the costs. But you may even want to think about index mutual funds instead. These two articles offer detailed suggestions for using the Couch Potato strategy in a small portfolio:
Become a Couch Potato Investor With Less Than $5,000
Should You Use Index Funds or ETFs?