It sounds like your experience with birth control over the course of the last 3.5 years has been consistent, so I'm wondering why you are keeping such an ardent eye on whether or not you could be pregnant. Of course, any type of birth control can
fail so it is worth it to keep an eye on your body & how it changes, but do you feel like this worry about pregnancy is super pervasive for you or keeps you from enjoying your sex life in any way? If not, we can just pretend I didn't go on this little tangent
I super recommend a few articles that may help you think about this further, too:
I included that last one because of course, pregnancy tests (and ultimately getting any positive test confirmed by your medical provider) is the only way to really know if you're pregnant.
Does any of this feel (un)helpful?