Here are some pictures of it.

If you are really watering it once a week....as per a schedule, you are overwatering it an awful lot.
You should water only when the soil surface feels dry...and poke your finger down to the first or second knuckle, feel any dampness, then let it go for another couple days and test again.

I'm surprised you have as much flowering at this stage as you do. The spring equinox is fast coming....the sun now is nearing the equator and soon it will be with us up here in northern zones so that growth will be supported.
Still, the sun's power is not all that good ...YET...but getting better.
The plant's wilting is a definite sign you are giving it too much water....its always the lower leaves that feel it first...they are the closer to the problem.

Let it go dry somewhat before you water.
This wilting, if it has been going on like that for some time, I'd suggest you un-pot the plant and inspect the roots.
Its not a bad time to do that anyway....pels are just now coming out of dormancy as many people do it...they've let their plants rest for the entire winter and now are bringing them out, cutting them back, re-potting with FRESH potting soil, making sure there is a barrier to the soil blocking up the drainage holes, and watering to drainage. Then giving it as much sun as you can...and that means into a western, southern, or eastern sun.
North light will not do the plant any good.

Turn the plant 1/4 turn every day or so, ensuring all parts get equal sunlight.

Whether you think you should cut it back at this time is up to you....ME, I recommend you do it...cut it back to about 4" - 5"....into fresh potting soil, into good light...and watch it come back good as new.