Spells work in subtle ways in order to influence, and manifest your intention through your will. If you set forth your manifestation through the act of magick, and it comes to you then it is most likely your magick manifesting, because your spell allows the probability of that situation to be more likely, though it may seem like a coincidence to you many different factors have gone into determining whether or not that state of being came to be, and it is the intention of your spell to bring that into your life, and to make it more likely.  Coincidences also more, or less do not happen because everything is determinant upon factors and your magick is simply an unseen subtle factor that you have ask to aid you in your life. Because, this process is so subtle it is actually quite hard to tell, but in order to truly figure out, if it was your magick or not you would have to continuously test the same spells again in another circumstance in order to see if they result in the same outcome.