Step up starter or pitch more yeast?

I picked up some material to brew about 3 weeks ago. I intended on brewing sooner but things came up in between. I went to go make a starter last night and ran into a problem. I logged on to MrMalty and punched in all my info. I'm making a 1.059 OG beer, 5.5 Gallons, Pacman yeast with production date of 9/13/2010. MrMalty stated in needed a starter of 1.45ml with 2 packets of yeast. I only had 1 packet of yeast with me at the moment. I went ahead a made a starter with what i had.

My questions is do I go out and buy another packet of Pacman yeast and pitch that with my starter or do I just push my brew day back and step up my starter? I have never stepped up a starter before so if that is the way to go how would i determine how much DME to use etc to make sufficient starter?

On the pitching rate calculator you can slide the growth factor bar to figure out the starter size using only one vial of yeast.

I realize that but in order to do that I would have to make a 3.6L starter and I only have a 2L flask. As with everything else with brewing I wish I would have just paid more $ and bought the 5L flask instead of trying to be cheap.