Okaaay, everyone will hate me for this. Or maybe not. But here goes...
When we took each of our three home after a short stay in the neonatal unit of a big London hospital, we were sent home with a leaflet on bottle hygiene, based on advice from the hospital microbiologist.
The gist was as follows (and this was for small, vulnerable babies):
Wash bottles and teats thoroughly with hot water and detergent. Rinse thoroughly under running hot water. Place bottles to drain on a clean tea towel. Cover with another clean tea towel and leave to dry.
As an afterthought, the leaflet added "If you want to use any of the conventional means of sterilisation, you can."
I offer this only as a comment, not as a suggestion. I confess that I never sterilised after reading that advice (was bfeeding, but used occasional bottles of EBM). We either did as above, or put bottles in the dishwasher (as did several GPs we know). Never had any problems, but I am a rubbish housewife, so they were probably immune to all the bugs anyway.