Wow, thanks! I am glad to know I haven't been mispronouncing all those words (well, in any way other than my American accent!). I have felt the tendency to do the ceceo, though, when I am speaking very quickly and the sentence contains a combination of C/S/Z. That gets really tricky, as I have trouble switching rapidly between the interdental and the regular "sssss" sound.
It reminds me of trying to roll the "rr," which took a long time to learn!! I had a teacher who told me to say, over and over again, "pot of tea." After a while, it becomes "para ti," with a nicely rolled little r in there. It's not the "rr," exactly, but it's a good way for Americans who can't do that to get started.
What letter sounds in English give Castilian-speakers the most trouble? I notice the little "es" in words that begin with "s" (esmall rather than small) sometimes. Why is that such a hard thing to learn, when Castilian speakers don't seem to say "esalamanca"? Is it "s" followed by particular consonant sounds?
Tara