Welcome to the forum!
The lowly 18-55mm is actually a quite good close-up lens, and it seems you learned to use it well. The Crime Unit Unit officers who work our homicide scenes do most of their scene photos with the 18-55mm! It is what the PD issues them. (I work patrol photography, and unless content to use a P&S, have to buy my own equipment; I have a 100mm 2.8L.) The 100mm, being of a longer focal length, is going to "see" things differently than your shorter-focal-length lens, as Plymer just indicated. Please provide more detail, and perhaps some images, to help us help you.
One thing to keep in mind is that at very close distances, manual focus may become necessary, especially if there is not plenty of light.
Another thing is that depth-of-field becomes VERY shallow at close range; the photographer may need to stop-down the aperture considerably in order to get enough of the subject in focus. Indeed, a main feature that distinguishes a true macro lens is its ability to be stopped-down far more than a typical lens.
I will add the disclaimer that I am NOT an expert.
Canon 7D/5D/40D/1D2N; Nikon F6, D700, FM3A, & Coolpix A; Canon 40mm 2.8 STM, 135L, 50L, 35L, 50mm 1.8 I, 100mm 2.8L Macro, 10-22mm EF-S, 28-135 EF, 400mm 5.6L; Nikkor 50mm 1.2 AI-S, 50mm 1.4G, 50mm 1.8D, 16mm 2.8D Fisheye, 180mm 2.8D, 100-300mm 5.6 AI-S, 18mm 2.8D, Voigtlander 90mm f/3.5 SL II