Bird of paradise
What else can I do to help my plant-
Problems with these plants occur because of lighting, watering or pests, or a combination of these. You seem to be aware of the possible causes, and have addressed them. I thought that re-potting the plant might be something for you to consider, and then I found this:
Curling Leaves on Bird of Paradise Indoors
Container bound bird of paradise plants should be re-potted every few years or when they become pot bound. New soil is important in container plants to help provide nutrients. It is also important to give the plant enough root space. If the plant is root bound, it impedes its ability to uptake moisture and nutrients which can cause curling leaves on bird of paradise.
Situating the plant near a drafty window will affect leaf health as will allowing the container to dry out for too long. Leaves may also curl after a transplant, but they will usually rally in a few days after the transplant shock wears off.
I looked at these sites:
I'd also refer you to your County Extension Service for a referral to a Master Gardener in your area.