Yeast question

Hello,
As some of you may remember I made an Imperial Stout 8 days ago. The OG was 1096. 2 days before I brewed I made a yeast starter (1000ml), which ended up after the boil and ferment as about 400ml of liquid and a good 1/2 inch of yeast sediment on the bottom. Looking back I should have made a bigger starter and maybe even doubled it. Anyway, I drained the kettle through the cf chiller and began aeration with a pump and stone for about 10 minutes, I had to stop because the foam started to overflow the carboy. I used a 6 gallon carboy and had about 6 inches of head space. I swirled the flask of starter and pitched it at 74 degrees. I used a blow off hose because I thought this thing would go nuts but it didn't. It started fermenting in about 5 hours and was going strong for about 5 days but never foamed up through the hose like I thought it would. The bubbling has slowed to one burp a minute on the 8th day and there is still about 2 inches of thick krausen on top. Oh yeah, it was American Ale yeast. Should I let it go another week or rack it now? Will all the foam (krausen) disapear when fermentation is complete? I would not be concerned about it if I had pitched a bigger starter, 300-400ml just does not seem like enough for a 11-13 percenter!
Thanks

You're fine. I'd let it go until the bubbling has pretty much stopped, then rack it to secondary. Your fermentation started pretty quick, and that's what counts. I made a 1.100 Imperial stout that I left in primary for about 2 weeks before it had fermented out.