Thank, Solar Flare. May I ask what you mean by 'using aspects by sign rather than by orb'?
I started off with the assumption that Saturn does aspect Moon (and Uranus), which would makes it part of a Grand Trine, but then found a body of opinion that these aspects are too loose to consider. With so many different approaches it can get a bit confusing and difficult to work out which makes more sense. So all I really have to go on is what feels psychologically and experientially more accurate. A Grand Trine would have been nice to have, but based on experience, it sounds a bit too good to be true. An unaspected Saturn, on the other hand, would explain a fair bit.
An aspect basically means a certain amount of degrees between two planets. There are five major aspects: conjunction, sextile, square, trine and opposition. But the thing is that the signs can aspect each other too! Taking your Saturn in Gemini as an example, Gemini as a sign sextiles Aries and Leo (because they are 60° away from Gemini), squares Pisces and Virgo (90°), trines Aquarius and Libra (120°) and opposes Sagittarius (180°). What this means is when you find two planets in the signs that aspect each other, the planets make an aspect as well. In your case, for example, Venus is at Sagittarius 26° and Mars is at Sagittarius 6°. That's quite a long distance between two planets but since they're in one sign, they are considered to be in conjunction by sign. Aspects by sign also mean that out-of-sign aspects are generally now allowed, except when the orb is less than 3°. For example, Saturn at 1° Gemini and Moon at 30° Cancer can be said to be in a sextile relationship, even though Gemini and Cancer don't aspect each other.
An orb is a possible degree of deviation from an exact aspect when two planets can still be considered to aspect each other. For example, AstroDienst (the site where you created your chart) takes the orb of opposition as 10°. Taking your Saturn at Gemini 15°, it means that any planet lying within 5° and 25° of Sagittarius will be marked as being in opposition to your natal Saturn. There is no universal opinion on how big or small orbs should be, if the orbs should be different depending on aspects and planets or not etc.
Yes, surely you have to stay true to yourself and choose methods that seem to fit you best. Well, as I mentioned, I don't use the outer planets Uranus, Neptune and Pluto (and others) so I wouldn't say that you have a Grand Trine anyway. But decide for yourself!
There are a lot of astrologers with different opinions and I'm not saying that I'm 100% correct, I'm just providing my opinion on your question.