i bought dr brown bottles last week, (after harrison having really bad wind with TT) and i could only fit 2 at a time in my TT steriliser, i debated buying the actual dr brown one last week but decided on getting the cold water milton one and i definately prefer that one, it fits 4 of them in aswel as all the little fiddly bits (it should fit 6 normal bottles in with teats and lids) and some dummies. I still use the TT one tho because i make the milk up in the TT bottles as you cant shake the dr brown bottles to mix the milk, then store the milk in the fridge in the TT bottles and keep the dr brown ones in the cold water steriliser until im ready to use them, plus the water is sterile for 24 hours and the bottles are done within 15 minutes.
EDIT: i also only have 5 bottles which is fine! i wash the bottle out after using it then chuck it back in the cold water steriliser.