I used the JUDE UML tool when I designed the diagrams. It was quite useful. It had 2 drawbacks though. I can remember only one of them, which was that it was not able to draw packages in a component diagram. I got around that by drawing a package with the line tool.
I'm still working on my assignment, its taking me a lot of time. I am using Sparx EA 7 seems to be fairly complete altough I am missing some functionality that is provided with Star UML which lacks other features.
Anyway, congratulations you with your first success and I hope you succeed with the follow-ups.