As I answered you previously, it is illegal to view child pornography on line. Normally, federal prosecutions begin when the government takes over the sites' servers and then can tell who downloaded material from the sites or even more importantly who uploaded material to the sites. You also may not have even viewed child pornography. That in addition to your age, makes it unlikely that you will face prosecution.
Read the laws here: http://www.sexlaws.org/18usc_1466a [list on the right hand side]
Read a report on the matter here: http://ipmall.info/hosted_resources/crs/98-670_091006.pdf
There have been many cases against people who accessed child pornography and those prosecutions were successful. Merely accessing these sites creates downloaded pictures in the cache of your system. It also creates a record on the servers of the sites accessed.
Having said that, stop dwelling on the hypothetical in this case. If anything happens, consult a local lawyer immediately.
[This communication is intended as general information and not specific legal advice, and this communication does not create an attorney-client relationship.]