Give it three years before worrying about lack of blooms. It's probably putting its energy into growing roots since it's only just a year old in that spot, and you said it was small and fragile when planted. A lot of gardening is about patience . . . plants grow and flower on their schedule, not ours. Don't need to prune unless it has some reason to.

If you are feeding the impatients (?) a liquid fertilizer, make sure their fertilizer does not spill close to the hydrangea roots. Too much nitrogen applied on or near the left one can reduce its bloomage. The hydrangeas should do fine with a single fertilizer application in the Spring for the whole year so, more frequent applications than that can start to increase the level of nitrogen in the soil.

I don't generally fertilize - it depends on whether it's needed. I use compost or mulch which as it breaks down provides enough nutrients in my soil. For flowering plants, if fertilizer is needed (and IME in most cases it's not) you want the first number of the NPK formula to be relatively low, since as Luis mentioned, too much nitrogen makes leaves grow instead of flowers.