@Albatross2008

There is now a new class of medications for overactive bladder that might help you. The old medications for overactive bladder are anticholinergics. They have many nasty short and long term side effects. Among the short term side effects is constipation, due to their mechanism of action.

You can read about new treatment options at

Overactive Bladder Medication: Anticholinergics, Beta3-adrenergic agonists, Neuromuscular Blockers, Botulinum Toxins, Tricyclic antidepressants, Hormones

There is also a non-invasive procedure called percutaneous nerve stimulation which helps in about 60% of cases. I have started it for frequency and some false urges. I have a different problem than yours: I can hold urine for quite a long time, but I go too often and the frequency varies widely and depends greatly on the stress level, so timed voiding is not a viable option for me. I also sometimes have false urges in the evening, when I feel like I need to go, but then I sit on the toilet and nothing comes out. These are still all symptoms of OAB, just different manifestations. It is good that there are more treatment options now.

Percutaneous nerve stimulation is done weekly for 12 weeks. I have had it twice and so far no effect, but I have been told that people do not see an effect until after about 6 sessions.