Oo! someone asking me for advice?! So exciting.
Sorry I haven’t responded to this sooner. I have had my troubles with frosting in the past (and will probably have them again), so do not fret. However, your flat frosting could be due to a number of things: temperature of the room, temperature of the ingredients, and what I’ve been finding a big factor, the recipe. If it says room temperature, it needs to be room temperature (this goes for more than just frosting.) For a while I wasn’t happy with the way my cream cheese frosting was coming out, tasty, but usually runny. I’d see it behind glass at bakeries and wondered how it looks so much nicer. Then I tried a different recipe, and now my cream cheese frosting stays where I put it when I pipe it out.
I hope that answered your question. I hope to post my new favorite cream cheese frosting recipe soon.