Some women do like to go slow, but 8 months is a long time to know someone and then they back out over fear. It sounds like you gave her the space she was asking for but she is still backing off.
What I would suggest is calling her and asking her why she broke the date. Let her know that you care about her and ask her if she needs more time. If she does then give her another week or so then set up a dinner date. i Would suggest sitting down with her and letting her know that you care about her but all this space has you concerned. Communication is the key here. You both must talk about what the problem is and address it otherwise this relationship is only going to crumble more.
Let her know that you do not want to push if she is not ready, but that you do need to understand what is causing the problem. Unfortunately some women will ask for space when they really want to break things off.....but are unsure how to. The key is getting her to admit what the problem is so you can decide where to go from here.
It is not very fair of her to keep the relationship in a stalled state. While it may be space she is needing there are ways to deal with this and keep the relationship alive. Ask her if she would like to knock everything down to just a date on the weekends to give her space but to also keep the fires burning. If she is unwilling to do this then you will have to ask her what exactly she wants. Let her know you will not be upset with her, but that it is only fair that she be honest with you so you know where you stand in her heart.
The reality is she may break this off, then again she may wake up and see that this is a situation that must be dealt with so you both can move forward in the relationship. The fact is you can not continue like this without one of you resenting the other. At this point you have very little to lose by stepping up and letting her know this needs to be dealt with, unless you plan on staying by the phone and waiting for her to decide what she wants.