[Always *]

You'd be better of just getting a pregnancy test. 2 days usually isn't a length that I could consider to be concerning, but I also never used to pay that close attention before I went on the pill, not down to the exact day at least, just a general time. But I know how many people (including myself) would freak out (at least a little) if their period did not come when expected. So getting a pregnancy test will at least stop you from obsessing/stressing out over the unknown. Especially since, like Jodie said, stress can make it late--my period was 2 weeks late once because I moved half way across the country and was adjusting to a new place and university completely on my own, and the weird thing was that I wasn't fully aware of being that stressed out so yeah it's a consideration... I'd wait until you are a full week late and then get a test.
You might want to come clean to your mom. I understand if you don't want to tell her quite yet, wait until you do the test. But you should consider going on the pill which is something you'll probably need parental consent for since your only 14