I know there are other threads touching on this, but I don't want to hi-jack somebody else's.
I thought the analogue switch off was supposed to allow the digital transmitters to increase their power, but when my local analogue switched off the digital signal dropped right off too, now about strength 4 when before it was at the max of ten (these are tv set up figures so are just comparative).
It's now almost unwatchable, despite half a dozen re-tunes (on two different sets).
DSO isn't final until the last transmitter stops analogue transmissions. Until that time some of the digital multiplexes are on reduced power so they don't interfere with adjacent transmitters still broadcasting analogue. Like you we still have some at reduced power even though we were DSO'd last year. So I'm afriad it's a wait for another couple of years until all the digital multiplexes are at full power on the day the last analogue signal is finally extinguished. click here for more information on whats happening and when - you need to enter your transmitter.
It could be your aerial as digital needs a different group aerial to what you may have.From memory i think digital use a wide band aerial.I suggest you get a decent local aerial guy to look at your set up and go from there.
Just a thought. Are you receiving from a local relay rather than a main transmitter? The reason is after DSO many/most local relays are only transmitting a small subset of the channels available from the main transmitter it is paired with. These channels vary depending upon where you are located (ie in Wales you are likely to have their local channels but obviously you wouldn't have those in Norfolk!).