ANSWER - Ok, I'm going to respectfully ask the Wiccans to leave this thread now as I'm going to answer this question based on the beliefs of my own path and none of you will agree with me on this one!
Gone? Good (Merry Part and all that...)
Right then. There is no such thing as the threefold law. It was made up in the 1900s. Magic doesn't have a moral mind of its own, it is a power to be manipulated by the caster, not an independent entity to judge and punish you. To my mind threefold is bandied about in an attempt to limit the workings witches undertake. I'm not complaining, it's given us a good press of being charming folk unlikely to harm a fly (an excellent smoke screen for witches who do use aggressive magic) but in truth it has no validity in reality. It plays on the psychology that if you are told x will follow y people will automatically look for x and when they find entirely unrelated x they link the two elements together and the rule gains credibility in their own mind. The truth is that threefold is nothing more than hearsay, pop psychology and guilt.
The most likely explanation for your run of bad luck is coincidence. Equally you might have stuffed up the spell work (in which case hop to it and put it right).
There is one other point I would like to add. Threefold itself doesn't exist but the concept of guilt certainly does. There are to my mind two specific dangers associated with aggressive magic. The first is that if you do experience guilt as a result of doing it this can have a very negative impact on your psyche and spiritual health. This isn't the magic attacking you it's your own conscience on the warpath. Of course this is only a problem if you secretly believe you shouldn't be doing what you are doing... The second danger is opening yourself up to negativity. I firmly believe that a person witch or otherwise who opens herself up to nothing but hate will warp into becoming a hateful person. Balance is important. A witch who uses hexes and curses when she believes she is doing the right thing and who doesn't use them at the detriment of balancing herself with positivity (ie curses and nothing else) is unlikely to suffer any consequences from working curses and hexes.
Examine your intent, if you believe your hex was justified then you have nothing to worry about. If you don't believe your hex was justified then - strictly speaking - you still don't have anything to worry about but I'd put some more thought into your spells in the future if I were you and save yourself the guilt trip.