My parents caught me not that long ago, early this year. I was 15. Memorial day weekend. They found just about everything. I'm so glad they did, I rarely smoke weed anymore. The bud chilled me out as I was a pretty uptight guy but now that I only do it very occasionally it has really been a lot more enjoyable and I appreciate my life a lot more now, especially since my parents can really set me on a guilt trip.
Stop smoking weed for a while, stop the cigarettes entirely. Stupid stuff man, tobacco. Especially at 15. You'll get over it eventually, I have. My parents trust me again for the most part. Clean up your act and you should be good.