Its normal for your cum to change color, especially as you progress through puberty and mature. Generally it starts out clear, then it gets a little cloudy looking, but still mostly clear, then it gradually turns very cloudy and eventually becomes white. This process can take several months to several years, depending on how fast you go through puberty. As sperm counts increase a lot towards the end of puberty, it is not uncommon for cum to take on a yellowish color - its not always pure white. Yellowish cum is often an indication of a very high sperm concentration, or old semen that hasn't been ejaculated in a while (which also typically contains a high sperm concentration).
I would also like to point out that clear cum doesn't necessarily mean there isn't much sperm in it. Sometimes it just means that certain components of prostate fluid aren't present yet, but it could still have plenty of sperm to get a girl pregnant with. It's not just sperm that makes cum look cloudy and white - prostate fluid makes up a lot of that color. You can't see sperm without a microscope, but when there is a lot of them together, they do make the cum look cloudy and white/yellow.
<i>My avatar is a picture of my own sperm under a microscope. Pretty cool huh?</i><br />Drugs are garbage. I'm high on my own testosterone.