You mention wanting to take close-up images of flowers and such.... And maybe wanting to do some portraits in the future.
A macro lens can do both. The larger the aperture, the better. That's what allows low light shooting and makes for a strongly blurred background (for the portraits... in macro shots it's hard not to get a strongly blurred background, depth of field is so shallow).
I have two suggestions:
Canon EF-S 60/2.8 USM Macro lens. This would be my choice if macro/close-up shooting were a heavy priority over portraiture. USM focus might be quick enough for some sports, too, though most macro lenses aren't all that quick focusing.
Tamron SP 60/2.0 Macro lens. I have this lens and bought it specifically to have a compact lens that serves multiple purposes... macro/close-up and portraiture. The f2 aperture is a full stop larger than the Canon offers, which can be helpful for portraits in particular. Is is not as fast focusing and lacks some features such as USM and Focus Limiter that some macro lenses have to help speed up focusing, so is not very usable for sports or any sort of action shooting. However I have other lenses that work well for those purposes. This lenses replaces a macro lens, 50/1.4 and 85/1.8 in my camera bag. In other words, it lightens my load by serving in place of three other lenses.
The 50/1.8 is the cheapest lens Canon makes. It's pretty good optically. It's build quality sucks and it's AF is terrible (noisy, slow and inconsistent). But, hey, for so little money it's a lens a lot of people end up with as a first prime. Personally I prefer (and have) the much better performing 50/1.4, but it has it's limitations, too. Neither of these are true close-up/macro lenses... though they can be forced to focus much closer by adding macro extension tubes. Even so, they are not "flat field" designs, the way most true macro lenses are, so you will see softness in the corners and vignetting at some apertures, when forcing them to focus closer than they are designed to shoot. Still, for many flowers, for example, they can be close enough focusing. And both these 50mm make for pretty darned good portrait lenses, when used on a crop sensor cameras (such as yours, and some of mine).
There is also a Canon 50/2.5 Compact Macro. However it only goes to 1:2 magnification on it's own, needs a separately sold adapter to achieve 1:1 mag (which both the 60mm mentioned above can do on their own). That ends up costing more than one of the 60mm lenses. It also is not a USM lens, so is slower focusing (not much different than the Tamron SP). And, personally I prefer a little longer macro focal length, to have a bit more working distance from many subjects.
Before you buy, continue to use your zoom/kit lens to experiment a bit, as you have been doing. You can set it to any of the suggest focal lengths, tape the zoom ring in place to prevent it from moving, and get some idea how any particular focal length will work for you. It's also pretty darned close focusing. Can be made even closer focusing by adding macro extension rings, too.