weird kreusen question

I have active fermentation in my 5 gallon carboy- the volume is 3.5 gallons however. Its a stout and I pitched it around 70 on Sunday. I have had active fermentation- lots of yeast within visible floating around attacking sugars- from my small experience- everything looks as if I am good to go. But I have no kreusen on the top- just what looks like a very thin layer of creamy-ish c02 looking bubbles. Not infection.

Its my first AG - and its SG was 1.042 - pitched with nottingham- said to hydrate before hand - which I didnt do - just pitched the dry yeast.

Any reason why I wouldnt have a nice layer of kreusen on the top?

The last time I used nottingham, i did rehydrate it though, I only got about 1/2" layer of krausen. Could be just that style for that yeast. All have different results. Sounds like it's going fine.

Ive used Notty even with a starter( i make starters for everything) It doesnt seem to take off very vigoruously or krausen a ton. Great yeast though. Your good to go.