Chicken Advice Wanted!

So today is day 15 of my hen sitting on eggs and up till now everything has been fine. She is sitting on 8 eggs in a broody coop in the barn. I've left the front off the coop and enclosed a small area with hurdles so she has somewhere to get off her eggs and poo and eat and drink, etc. I take her off the eggs every morning to check that the eggs are okay but she usually doesn't eat at that time and runs straight back onto the eggs although I know she is eating at some point as the food keeps getting messed up, etc.

This morning I was out in the field and heard this horrible squawking from inside the barn -- ran in to find one of the eggs on the floor, cracked, and with blood oozing out (I guess this means the eggs are fertile at least!). I took the egg away and tried to check that the other 7 eggs were okay -- she wouldn't get off them, so I felt around under her as best as I could and all seemed fine. So I went back outside to finish my other chores and then a few minutes later popped back into the barn to get something and noticed that she was out of the coop again so walked over to her corner and found that another egg was on the floor and completely smashed and what looked like yolk mixed with blood all over the floor.

At this point I rang Greg who advised that I should put the front on the coop and confine her in there. Have done this but am not really happy about it for two reasons: 1. If she wants to eat, drink, poo, etc., then she can't until I next come and let her out. 2. My first broody hen turned out not to be a broody hen after all, and I feel that I don't want to force the hens into sitting on the eggs against their will, which is why I didn't put the front on the coop in the first place as I felt that if she was truly broody she would sit and didn't need confining -- so in the event that I am wrong about this one as well I don't want her enclosed in there... Also, for the duration of the last two weeks, she has been sitting with her head into the darkest corner of the coop and her bum nearly hanging out the open end. Now, since I've put the front on, she's turned around and is facing the opening -- so why has she changed position unless she's unhappy?

Any thoughts and advice would be most welcome as I am rather worried that I am doing the wrong thing!