You need to end the attack on the homestead before more portals will open. Check your quest log or talk to Zixzax; basically, you need to do something in norther Luculla Forest.
Destroy a large blood stone, using tenebrium damage.
Blood stones give experience when used, fully heal your party and resurrect and dead party members (and are used for a couple of side quests). Even without the connection to opening portals in the homestead, you should not have been discarding them.
The inert stones are not required, though if you keep them it does make it easier to keep track of how many blood/star stones you have found.
Stop the attack on the homestead, and see how many portals Zixzax opens (using some or all of the blood stones you have, if required).
That may finish off the portals (open all but the Forbidden Zone one), or at least get you close enough to be able to check a couple places on the list that you're pretty sure you didn't already get the blood/star stone from.
It is also possible to bypass the door.
Drop a teleporter stone in front of the door (I got it to work dropping on the left side, a few steps back), then drag and drop it from the past the door (rotate the camera to see; you might need to move the cursor around a bit to find a place where the pyramid is outlined in white and you can drop it).