A suitcase in a dream usually marks a transition already in motion, and what you're packing often mirrors what you feel you need to carry into the next stage. An overstuffed or impossibly heavy suitcase can point to a burden you're bringing forward that might be worth setting down first.
If in any nativity Mercury shall be in the ascendant, oriental, and swift; the native will be eloquent, and learned in the liberal sciences: the same happeneth, if he shall be in Sagittarius in his proper terms. - William Lilly (1602.-1681.)