Hello 😊 I would advise you keep your gastric movement as healthy as possible, as long as possible!!
It sounds like you've been using fiber based methods to get things moving, and you definitely want to stay away from stimulant laxatives, as the body will become dependant on them.
Have you tried water pulling lax such as Miralax? If you're okay with drinking plenty of water, this could work in a different way, and also has less risk of dependence.
An eating disorder inpatient unit would provide much more structure. They can really help, but if you're not open to the change, it won't stick.
If you're open to inpatient, and it's available to you, go for it!