Telling you they need to go takes time, and from what I've read, it takes them a long time. My daughter tells me or takes herself the bulk of the time, but she still doesn't always get the timing right (they are young, and easily distracted after all!)
My daughter was in trainers at 18 months, and 99% trained, night and day at 23 (we are having a slight nighttime regression, but she will stay dry if she is in her cloth diaper and not her undies!)....
In any case, it took me 3 months to get my daughter to put her poop in the potty. I let her poop everyday in her cloth trainers (messy!) and we would go to the bathroom and clean her up, and flush the poop down the toilet. Everyday you need to make a ritual out of flushing the poop. Also, I read her "everybody poops." I found this really helpful to get her to stop hiding. I don't know if it might help with being scared of the potty?
If I was you, I'd discuss going poop on the potty with her everyday, trying to find out why she doesn't want to use the toilet. I'd also think about not letting her have the diaper. I really think they are either "too big" for diapers or they are not. So, if you are truly committed to potty training her, then you need to say good-by to diapers, including pull ups, and put cloth trainers on her. Yes, it will be messy. Yes, it will be frustrating, but it will give her the chance to learn more about control and timing. Save the pull-ups for bed and naps, and commit to her being "too big."
Then, get yourself a schedule. Part of potty learning is teaching potty etiquette (you go when you wake up in the morning, before leaving the house, etc). Eventually, they will then just take themselves or tell you they need to go.
So tell her that starting tomorrow, she is "too big" for diapers, and get her some fun trainers. Then, go let her pick out some terrific undies, buy some fruit snacks or another treat she never gets, and tell her then when she puts her poop in the potty, she gets to wear her special undies and have some fruit snacks. My daughter was so motivated to wear her "elmos" and have "dora" fruit snacks that it took me only a few days to get her going poop on the potty (once I figured out something that motivated her). At the end of that week, she not only put her poop in the potty everyday --taking herself off to do it!- but she also woke up dry every morning.
It's all connected, so if you can figure out how to get the poop in the potty, you should see great strides in her overall training.
Good luck and hang in there! And get your potty dance ready! Praise is the best motivator, I've found.