Hi lycheefan, as you have recently started the pill, it is important to note that your body is setting up a pattern of how it will respond to it. Some people get heavier ones than others, and some people don't get one at all. Why the information you are finding is inconsistent is likely because some people don't get a withdrawal bleed at all and that's just the way their body responds to the pill. So not having a withdrawal bleed in and of itself is not a
certain indicator that someone is pregnant.
However, a sudden lack of a withdrawal bleed for someone who usually has one is an indicator of some kind of change, which may just be stress or other kind of hormonal change, and pregnancy will cause hormonal changes. However, with a pill used as per its instructions, and even moreso when used with a second method of contraception, like condoms, the likelihood of this being the reason is really, really small. Like, 1.3% small, with typical use (
as the combination of these methods is 98.7% effective with typical use, 99.99% effective with perfect use).
Keeping aware of your body's response to your birth control in and of itself is a useful thing, as if you get any changes to the pattern that your body establishes when taking the pill (which is something that can take a while to establish), this can be worth bringing up with your doctor. Often, it will be within the realms of "normal" for someone taking the pill (prolonged pill usage might see these withdrawal bleeds become lighter with time, or not), but is still worth noting more in terms of maintaining use of a suitable kind of birth control for you in terms of health and comfort over time. Does that make sense?
Below are some articles about how the pill works that you might find useful, as they shed a bit more light on how it works: