I can see why you'd be anxious, between your miscarriage and irregular cycle. First, if you haven't already talked to your doctor about your irregular cycles, I would bring it up at your next checkup. If you ever do decide to actively try to get pregnant, you'll want to get down to the bottom of why you're having irregular cycles.
At this point, since your last period was lighter than it usually is, I'd pick up a pregnancy test. If it wasn't your actual menstrual cycle, but instead a symptom of early pregnancy, the test would be accurate at this point. If it comes back negative, then it was probably just a wonky period and I would purchase some of those "internet cheapie" pregnancy test strips. I'm suggesting this because they can be really helpful for easing anxiety on whether or not you're pregnant. They're not as sensitive as more expensive tests, but at about $8 for a month's worth of tests, they're worth it! These things are just skinny little tests that come individually packaged. You dip them into a cup of your urine for a few second then lay it flat. After about 5-10 minutes you'll see either one line, for a negative test, or two lines for a positive test. Anytime you're worried that a period may have been more than a period, or you're experiencing strange symptoms in the few days leading up to your expected period, or if it's been a while since you've had one, you can take one of these cheapies for reassurance.