Not only does it assume necessity but it mentions it. ''Do not multiply entities beyond necessity....absolutely no dismissal of necessity here.
Not the same type of necessity as you are claiming in your arguments - Occam doesn't consider something that is necessary to not be contingent, merely that it is required for that explanation. Effectively the explanation with the fewest assumption is preferred.
But if you think that Occam's use of necessary is the same as yours (I actually don't think you do) then you really have shot yourself in the foot. You think that there must be one necessary entity and one alone. Occam is happy with one, two or two thousands necessary elements - all Occam wants is the fewest.
So back to your Occam justifies just one and only one necessary entity, let's try an example.
Imagine you hear the sound of an owl in a tree - which of the following fits Occam best:
1. I assume there is an owl in that tree.
2. I assume that there is one and only one owl in the tree
Occam plumps for the first - there could be loads of owls, some might be asleep, you might be hearing hooting from more than one owl. To limit the number of owls to one and only one falls foul of Occam as it adds an additional, unnecessary step.