If you can reach down, hold your open lips apart, put the container so the entry to the urethra (in the area between your clit and the entry to your vagina - if you can get to check out where it is with a mirror it is helpful so you know exactly where it is) is in the middle of the container.
That's what I was going to suggest too but I think it's a lot easier without a preggy belly in the way Worth a shot though.

I can't remember what I did, I think I just weed on my hand You could always do it in the shower then wash yourself straight away. A bit gross but it would make the clean up a bit easier

ETA: Sopdet - I should have read your entire post! SNAP!