If you're just learning astrology, two books that I highly recommend are Stephen Forrest, The Inner Sky; and Robert Hand, Planets in Youth. Both authors, especially Forrest, take a dynamic view of human beings and their horoscopes.
Sun opposite Saturn can be one of those aspects where it "hurts to be you." Saturn often shows where we feel inadequate in life, and the sun is your sense of self, so with this aspect there can be a sense of something being intrinsically wrong with you. (I have this aspect, too, BTW, though not such a tight orb.) Ditto for Saturn squaring you moon (feelings.)
See if it helps (as it did for me) to study Saturn, to understand him as the wise but stern teacher whose lessons are hard work, frugality, and patience. Because Saturn rules fear, he also teaches courage. An old but still worthwhile book on Saturn is Liz Greene, Saturn: A new look at an old devil.
Sun square Pluto can hit your self esteem, as well, but a more positive interpretation is that you are an ongoing stand for self-transformation.