New lawn coming in slow, tips/help?

Had landscaping company install irrigation, loam and hydro-seed last fall (09/10) and watched the lime green fuzz (seedlings) come up til mid/late October. The gr only came up about 1-2 inches. Then it seems the gr went dormant and stopped growing. I didn't put winter fertilizer down figuring I'd wait til spring to see what growth there might be. I didn't see growth like the established lawns in the area so I bought Scott's Starter Fertilizer 20-27-5 and spread it on a slightly lower setting than recommended (late 4/10). I had expected the shorter gr to start to spread out and fill in the thinner looking areas but it hasn't really so I just reseeded 1.5 weeks ago today, with some Evergreen Seed from Blue Seal (A versatile and dependable sun and shade mix. Produces a lush dark-green lawn that thickens rapidly after germination.) I don't see anything happening yet. How much longer should I give the seed before I fertilize again? And what kind of fertilizer should I use...another dose of starter fertilizer or turf-builder type? I finally mowed last weekend to even out the gr length, but the seed had been down for over a week by then. Thanks in advance!