Your question actually brings up one of the toughest things about psychological research that exists. While one can use the scientific method to analyze the data, COLLECTION of that data is anything but objective because it's based purely on perception--yours or someone else's--instead of quantifiable data. Sure you can use an intrument to track it, but, for instance, there's not any kind of objective measure of when "irritated" becomes "mad".
That being said, there are a number of instruments used to scale mood, and a good article to start with is here. Again, these are all based on subjective observation or self-reporting.
Given the situation in your question, though, I'm not sure these instruments will be helpful. What you're trying to attempt is an excellent exercise. Self awareness of mood patterns, and looking for triggers to help less productive moods become more productive moods is an interesting thought exercise, and could yield some great results. However, the recording methods you describe are of more concern to me.
First, many of the instruments will use simple terms like tired, sad, frustrated--so you're already doing essentially the same thing as the more scientific methods. If you're trying to see patterns and triggers, you may wish to consider adding a quick note about WHY you're tired, sad or frustrated. Did you stay up too late? Are you thinking about a friend who moved away? Is your team not giving you information that you need to move to the next stage of a project? In addition to understanding your moods, understanding the triggers is equally important to making the changes you want.
Second is consistency. You say your recording is irregular. Any of the more scientific instruments will necessitate recording at regular intervals. Because you're looking for patterns, tracking mood over time is important as well.
I would suggest that you've already got a system in place, but it's nt working because you're not providing yourself enough detail, and you're not making it a habit regular enough to collect meaningful data. More scientific scaling will require more scientific methods to gather the data, but if you're not using those methods now, a good question to ask yourself is why? Just because you get a new page format on which to record the information, how will that make you record it more regularly? Just because you have a different set of words to record your moods, how will that make you place a tick mark every hour?
I'd suggest that your problem is not in WHAT you're tracking...you seem to be doing fine in that regard, but HOW you're tracking it to produce meaningful data. This may require a re-analysis of your goals so you can understand what you need to understand and which data you need to collect to understand that.