how do you know they have done nothing or are not planning anything?
you have done your bit - you are not 'part' of anything so why would they keep you informed?
did you think theyd swoop round to your flat and set up a temporary headquarters and involve you in everything, appointing you honorary detective?
no, obviously not.
the reason you dont know what they are doing is because its nothing to do with you - they are the police, not you, and whatever you might 'think' is going on, it is not 'evidence' ... it is your opinion and judgement.
for all you know plain clothes could be hanging round watching, they could have taken an empty flat in the building to monitor - point is they arent going to tell you.
(you are probably correct... but they need more than what 'you reckon')