Avoid foods that cause constipation... Milk, cheese, white flour,fried foods, beef....
Take something with fiber like Metamucel.
Drink lots of water, preferably warm
Take stool softeners or use suppositories.
Mind you, I'm not a doctor, but is this something recent or a continuing problem? You said 12 days, the later typed 6 months...
I had a daughter go through this in grade school. When she did go, OMG!!! Only took like 4 or 5 flushes!!! Tried softeners, juices, fiber tablets, everything you can think of. (She was only going very 7-10 days) Later her doctor and I thought it was the stress of me going back to work; I wouldn't be home all the time when the kids got home! Are you having any type of stress lately? Just an idea. I'd check with my doctor if this continues. You have to be so uncomfortable by now. Good luck.
P.S. You mentioned you are scared to have a BM? Why would you in the first place?