This website contains your birth chart and your personality traits based on your chart:
http://astro.cafeastrology.com/cgi-bin/astro/natal?member=&recalc=&name=&sex=t&d1day=20&d1month=12&d1year=1989&d1hour=14&d1min=50&citylist=Boston%2C+MA+%2825%29%2C+United+States&lang=en
To know your most dominant sign(s) in your chart, you have to really look deeper into your chart, e.g. look at the aspects each planet is making with other planets, the points (degrees) and the houses each planet is placed in. To do this, you’ll have to place all of your planets into your houses, look at the degrees of each of your planets, and how much a sign is influencing your chart based on those degrees. Luckily, the website above will show you your chart (your signs and their degrees), your houses (ascendant, descendant, mid-heaven), and will give you a table showing each planetary aspect with regards to the planets placements with others (conjunctions, oppositions, square, etc...), and it will also give you an in-depth description of your personality based on those planetary aspects.
However, what the website doesn’t pin down is your Decanates and Dwads (Duads). The website below will give you a description of Decanates in a person’s chart.
http://www.skyviewzone.com/astrology/decanates.htm
However, there isn’t much on Dwads in astrology. Only professional astrologers know of this term, even though it is rarely used (though it is somewhat important in a person’s chart). Here is a forum about Dwads....you'll have to scroll down to find "Alice McDermott's" entry where she explains everything.
http://www.astrologyweekly.com/forum/showthread.php?t=1216
This may or may not be difficult for you to understand, but just in case I’ll work out your dwads (duads) and decanates for you....
Sun: Sagittarius
• Decanate in: LEO
• Dwad in: SCORPIO
Moon: Libra
• Decanate in: LIBRA
• Dwad in: CAPRICORN
Mercury: Capricorn
• Decanate in: TAURUS
• Dwad in: LEO
Venus: Aquarius
• Decanate in: AQUARIUS
• Dwad in: ARIES
Mars: Sagittarius
• Decanate in: SAGITTARIUS
• Dwad in: SAGITTARIUS
Jupiter: Cancer
• Decanate in: CANCER
• Dwad in: VIRGO
Saturn Capricorn
• Decanate in: TAURUS
• Dwad in: GEMINI
Uranus: Capricorn
• Decanate in: CAPRICORN
• Dwad in: PISCES
Neptune: Capricorn
• Decanate in: TAURUS
• Dwad in: TAURUS
Pluto: Scorpio
• Decanate in: PISCES
• Dwad in: TAURUS
North Node: Aquarius
• Decanate in: GEMINI
• Dwad in: VIRGO
Conclusion (Dominant Signs, Elements, Planets)
P.S. The dominant planet is worked out by the house system; because your dominant sign is Capricorn (according to the planets), and your ninth and eight houses is ruled by Capricorn, then your dominant planets are Jupiter and Pluto. This is because Jupiter rulers the 9thhouse and Pluto rules the 8th house; your Capricorn Signs are therefore influenced in these houses. However, because none of your houses are ruled by Taurus and Scorpio, then, for example, your Taurus signs are influenced in between your 1st and 12th house, but is more influenced in the 1st house (look at the degrees), ruled by Mars, therefore your dominant planet (according to your decanates) is Mars. This means that the signs/planets in these houses, and the signs in these planets are stronger than others in your chart.
Planets (Dominant Sign: CAPRICORN / Dominant Planet(s): JUPITER + PLUTO)
• 6 FEMININE, 4 MASCULINE
• 6 CARDINAL, 2 FIXED, 2 MUTABLE
• 4 EARTH, 2 WATER, 2 AIR, 2 FIRE
Decanates (Dominant Sign: TAURUS / Dominant Planet: MARS)
• 6 FEMININE, 4 MASCULINE
• 3 CARDINAL, 5 FIXED, 2 MUTABLE
• 4 EARTH, 2 WATER, 2 AIR, 2 FIRE
Dwads (Dominant Sign(s): TAURAUS + VIRGO/ Dominant Planet(S): MARS + SUN)
• 6 FEMININE, 4 MASCULINE
• 2 CARDINAL, 4 FIXED, 5 MUTABLE
• 5 EARTH, 1 WATER, 1 AIR, 3 FIRE
All Points/Planets (Dominant Sign: CAPRICORN / Dominant Planet(s): JUPITER + PLUTO)
• 18 FEMININE, 12 MASCULINE (Ratio 3:2)
• 11 CARDINAL, 11 FIXED, 9 MUTABLE
• 13 EARTH, 5 WATER, 5 AIR, 7 FIRE
I hope this really helps you - it took me ages :)