One of the ways to keep yourself accountable is to set some goals for your website. This is an excellent way to measure your achievements, but remember that your goals should be time-sensitive and specific. Here are some examples, which should help you get started:
As you see in the examples above those are quite specific goals, and you will be easily able to say if you indeed achieved your goal or not, which is very important. You can also measure to what degree you accomplished some goal in percentages. Some people even set goals for themselves every month and say that it keeps them motivated. My personal advice is not to set goals to high, so that you will not get disappointed. Of course, realizing hard to achieve goals can be a very rewarding experience so it might be worth a try.