Spotting on BC

I started taking loestern 24 three months ago. During the first two months I never had any spotting or other side effects. I was told to wait a month before having unprotected sex just to be sure that my body had adjusted to the pill. For the last two month my boyfriend and I have been having unprotected sex. Then last weekend (one week before my period was suppost to start) i started spotting for about a day. I know that it usually takes your body about 3 months to adjust and my doctor told me not to worry if I started spotting or things like that. But I was just wondering if since I had no spotting for the first two months is it still normal to have spotting during the third? Also, I know that my chances of getting pregnant are slim, but could that be possible as well? Finally, my periods have been a lot lighter (like 3 days and I don't even need to wear a tampon, just a panty liner) so since I was spotting last weekend is it possible that I might not get my period this weekend like I'm suppost to and still not be pregnant?

I should also add that I take my pill on time every day, except for one day when I took it like a half hour late. Last month I only took two of the four inactive pills, and I know that they don't affect the effectiveness, but I still am freaking out about it. Sometimes, like on the weekend, when I don't wake up as early I take it without water and it almost feels like its stuck in my throat, could that decrease the effectiveness?

I know that it probably sounds like I'm being paranoid, and I probably am, but I just want to be sure! Thank you so much and I'm sorry if none of this makes sense.