How to replicate tissue pattern using swatches in Illustrator?

Using swatches in Illustrator I want to replicate this pattern:

I think to use swatches is the fastest way to replicate this pattern. But I can't get it done right. Firstly I drew those little ellipses and copied them to get this pattern:

Secondly I applied clipping mask to it and dragged the result into swatches panel.

Then I drew a rectangle and clicked on the swatch I have just created. The rectangle wasn't filled completely with dots, here is what I've got:

Also the pattern of that tissue I created doesn't look look real. I just applied gradient to ellipses.

Please help me create that pattern using swatches and make it more lifelike.