I have never really used a bridge camera but a good friend of mine uses a panasonic bridge all the time and gets some good results
some of the shots that you have posted are very good and you should be proud of them, one of your latest sets from bristol shot through the fence, that is somthing i wouldn't be able with a DSLR as i do not have a lens that will fit through the fence, one of your other sets that comes to mind is your shots from Brussels Airport again some very good shots
the trouble with the Step up to DSLR it can be very expensive and often the cheaper entry level kit will not give that much better results than you are getting now, nothing wrong with the entry level DSLR,s but often the entry level lenses are what lets the side down, a cheap 70-300mm lens can sometimes give disappointing results
if you want to move up to DSLR then would you consider second hand as you can get some very good quality secondhand kit for not much money, late last year i sold a Canon 50D which when new cost north of £800 five years on it sold for £180.00 with a very low shutter count of only 15926 and the canon 50D shutter is good for 100,000 plus clicks, so it was a very good camera for not a great deal of money also some good second hand lenses to be had like the lens below
http://www.ebay.co.uk/itm/Canon-70-300m ... SwG-1WtoE7
a good second hand 50D and a lens like the one above would be a good starting point then you would need to add a short zoom lens as well so already you would be pushing your top budget and some more
