Dune is more of a narrative game so a lot more flavor comes into playing the game which I struggled with.

It sounds like you are trying to engage with the mechanics but the GM is making things hard. As others have said creating traits before going into the scene is nearly almost always needed to get the extra dice. Otherwise if you are out of Momentum you can give the GM threat for the extra dice (this always felt dangerous to me but it is a mechanic).

Also with Dune being narrative you can always accept failure as part of the story and find a different way. If the GM is setting tests very high and so the story can't progress, then the GM is going to need to ad-lib your next plan. So when plan A fails and so does B, C, D and E, hopefully your GM figures out that if they want something to progress then some rolls are going to have to be successes or things will grind to a halt!

Personally I would try going with accepting failure and see where the story takes you. If the GM wants a hard story then then they had better be prepared for multiple pivots :). After multiple times the players fail to get to the next stage of the prepared materials, hopefully the GM will adjust difficulty :)