Thank you to everyone for all the immensely helpful replies.
I've started to discuss these things with Laura and wanted to update in response to everyone that has helped.
You know what's interesting?... I originally posted this question in the hope of finding ways that I could be less selfish and encourage her to enjoy herself, without bogging her down with the (as G.Girl says) 'ping/pang/pongs'.
I have honestly felt like I am too sensitive for poly, that my expectations on being asked how I feel about something *before* it happens (she is genuinely good at asking *after* a date happens) are too high and that I have a more monogamous mindset. I have felt like I have an end goal of "someday, we will hardly ever feel jealous, threatened or neglected and nothing much will bother us".
Whether I have unintentionally put my question across in a way that has elicited these responses, or whether I just wasn't seeing it... it has definitely given me food for thought.
So in update - I have talked to her about the fact that she needs to let go of "I'm the hinge - it's more stressful for me".
I also talked to her about polysaturation. She has now had two dates with a good guy and is ready to make the step to sleeping with him - her first other person since we got together 16 months ago. She has made a very conscious effort to pick someone we all like, that fits for all of us, and to introduce us to him. I did ask if that meant the end of dating for a while, outside of him. She said that it will slow, but she will continue to meet the odd one or two people, if they are interesting, just to have them in the picture for casual events. I wasn't entirely happy with the response; but can see why she wants to carry on.
Finally, she asked how she could have made her dating any easier, when I came back home to the UK in May. I told her that had she *asked* how Mark and I would feel about her hitting the dating scene again, *before* launching herself and us into it, I don't think there would have been as many problems at all. We could have said, "please give us a couple of weeks... it's been a big time of adjustment... then go for it; we want you happy." We would have felt part of it - whereas we ended up feeling like onlookers. Incidentally - her response was that I was making sense, but that she'd already put it off for long enough, for my sake, and waiting any longer would have gone completely against her needs, as she was already denying them. She feels that we shouldn't put time restraints or "permission slips" on each other.
In conclusion, to use G.Girl's surfing analogy - yes: there seems to be a philosophy that our poly V is slightly more weighted towards ensuring freedom and cheering on the person who is surfing the waves (whichever one of us that may be), than about working as a team to ensure everyone's having fun - surfing the sea, or sitting back on the sand.
So end of rambling... I think my epiphany is... she says that she considers us all the time, by holding herself back from doing certain things, when she would have jumped on them if she was single. But maybe the way
that she considers us (i.e. denying herself rather than us coming up with a plan together) is the problem - it's ineffective. I don't want her to hold back - I want her to decide *with* us.
I'm not ending the thread: if anyone has input, I'd still love to read it - just wanted to make sure I'm not banging the same drum. If there's more to say, I'd love to hear it - and if there isn't; thank you all again for your help!