that plant is rootbound, you should cut off that bottle and put in in a slightly larger container (cut, because its a bitch to get those off usually. and cut very gently with very sharp knife, dont hurt the roots much, if at all, but check if the plant doesnt just slide easily out before you attempt cutting. (not too difficult though)
if the plants keep on drooping like that, even if freshly watered or not quite bonedry, they are usually (100% for me so far) root bound.
it wont need much extra soil, maybe an inch or an half, flowering plants dont grow much roots, but being rootbound will stunt it nonetheless.
its better to water before plants get droopy,btw, just figure out what how heavy the pot is at the right time, easiest way. and you should completely drench your soil till runoff comes out the bottom, preferably quite a bit of runoff, flushing the soil bit and completely saturating the soil, allowing the roots to completely fill the rootzone, not just concentrating on the bottom of the container.
nice looking plant btw