I am 31 years old, but first started having issues around your age. I almost had to drop out of college. The first thing I remember is debilitating tiredness. All the time. Then, I got sick very easily. This progressed to chronic sore throat, lymph nodes swollen, muscle pain, joint pain, poor memory and cognitive impairment ( i got lost going places i had been before!) My doctors did not know what to do with me, they tested me for Lyme disease, mono, you name it. I had blood tests run which all came back "normal." But even if your blood tests are within normal range, it doesn't mean its normal for YOU, especially if there are a cascade of ill effects going on.
Your first step, before you run out and buy cleanses or convince yourself of heavy metal poisoning (I am not discounting that, I just think it best not to jump to vague theories), is find a doctor that is experienced. I went to a doctor who specializes in CFS. I was ultimately diagnosed with CFS, and had hypogammaglobulemia (mainly, a low subclass of IgG of unknown cause). I was negative for adrenal and thyroid issues, but did have iron deficiency. You need to rule out those type of causes of disease first, and treat them if found. My primary care doctor tested me and my iron levels came back normal, but the tests my specialist did were more sensitive and told a different story.
I still have issues, and am currently planning on more tests, like Lyme. Standard Lyme tests are only 50% accurate, so you really need to find someone who knows what tests to run. Don't let people tell you its depression. I was told I was depressed for YEARS. I do suffer from depression, but its not the cause of all my problems. Depression is an easy category to put someone in, because there are a lot of side effects that are vaguely related.
My other advice is start using all natural body care products (many products contain estrogen mimics which could exacerbate your situation) and try to by organic to reduce your pesticide loads. Look into your medications. Hormonal birth control is often prescribed to people your age, especially for "regulation" or Acne treatment. Long term use of them can cause a lot of the symptoms you display for instance. And good luck. Find a doctor that takes you seriously. You can also look into an naturalpath Doc to balance your treatment (just be careful, they often make $ selling the products they tell you you need, so make an informed decision on what you might follow)