It looks a bit small, you're right - but not bad, for one week. I almost gave up on my first grow, but they really took off after two weeks or so. Now they're flowering like Mad, they've grown too tall for my tent really - so don't be too quick to give up.
How far away is the Light? I'm using an El Cheapo Chinese 1,000w LED light, and I moved it down to about 15" above my
tiny seedling, until I saw the edges of the leaves JUST beginning to burn...then I backed off to 18 inches.
I'm learning as I go, and here's the plant I almost gave up on, 7 weeks ago. Nearly four feet tall. It was only supposed to be 2 ft tall! I'm now feeding it some mild mixes of Flowering fertilizer. Come on, buds! Fatten Sesame!