Concerns:
The plant is very droopy.

Darryl
Thanks for the photos and info!
Environment:
This window and position looks adequate in terms of light.
Effort:
The watering strategy for a begonia is only to wait until the soil is partially dry – not completely dry. In fact, with excellent light, you can keep the soil evenly moist for excellent growth. You should use fertilizer to ensure the plant keeps producing new leaves and keeps a good number of leaves on each stem. Suggestions for fertilizers HERE.
Expectations:
A cane-type begonia will eventually get too tall to stand on its own – this is just how they grow. You can either prop it up with a chopstick or cut back the stems – the cuttings can be propagated (root in water, sphagnum moss, or perlite) and the stumps will push out new growth as long as they are healthy.
Front of my Begonia ‘Miss Mummy’:

…and the back – supported by a chopstick and soft wire ties:

If you want to develop strong fundamentals in plant care, my book and online course will guide you in the right direction.