Something I have found; is that it helps to have a set time to come back to the table. So-for us we have agreed that every 3 months we will look at our agreements and see if they are "still working for us". That way if one of us feels a need for a change, we know it's possible at that 3 month mark to address it.
But-we don't discuss it at any other time-unless it's AN EMERGENCY situation (and frankly-there hasn't been such a thing-because most poly situations aren't emergencies).
It also forces us to follow through on our commitments regardless of NRE. So for example; if one of us meets someone and we want to change our agreement for the benefit of this new relationship; we can tell them our negotiation time frames (Jan, Mar, June, Sept). (We intentionally made the first time frame awkward to avoid Christmas season and our anniversaries (mine with GG is in April and with Maca is in July). That doesn't mean that the change can't happen. But it does mean we aren't going to just start demanding changes because we are caught up in NRE.
Its important to understand that your gf doesn't have to ever accept being in a relationship as open as you would like. That's her right. You don't have to accept being in a relationship as closed as she would like. That's your right.
But if you want to be together there needs to be compromise. Compromise by its nature means you both get SOME of what you want-but not all. It sounds like she's offered a compromise. Whether it's reasonable enough for you-only you can decide. But it's certainly not what she wants and it's more towards what you want, even though it's not everything you want. That makes it a reasonable offer AS A COMPROMISE.
If your highest priority at the moment is not losing her; it may be reasonable to agree with the caveat of wanting to re assess if it is still working for both of you at some specified time in the future. That stops the fight and allows time to "see how it goes" but also keeps it clear that this isn't necessarily going to be feasible forever.
"Love As Thou Wilt"