Without taking a hydrometer, you have no idea what your beer is doing. Krausen on top means nothing. Airlock bubbles mean nothing. Thus, you are confused, but thinking along the right lines.
Hydrometer readings...that's where its at!
Many yeast strains leave a thick head behind, so yes it is time to at least take one hydro-reading, since you need 3 days of stable readings to judge anything.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10