C++ programming language is more a reference book (at least that is how I use it). I don't know the first two books you read, but if they gave you a good basic understanding of C++ then I would try to start a project. This is the best way of learning a programming language for _most_ people (including myself).
Start small, if you're stuck take the C++ programming language book(or google) and try to figure out as much as possible about the thing you're stuck with. If you're still stuck or you managed to move on but want to know why something happened etc. then post here ;).
I agree with thelamb that Stroustrup's book is more of a reference work. Well worth keeping on the shelf handy for quick sanity checking, or getting into stuff in depth - that's what I use my copy for, along with the Annotated Reference Manual (ARM). I've been programming in C++ for 20 years, and I still use them regularly.