My two cents is that this is the most useful approach in order to gauge the situation. But you must be prepared to postpone moving in together in my opinion and watch how she behaves.
Do not move her in at this time. If you live in the US you are creating a situation where you CANNOT just order her out. She will establish residency at your place (irregardless of whether or not she is on your lease) and you will not be able to require her to move.
Think long and hard about that. Perhaps a recent experience I have had (as a landlord) may help you see my point: Last summer I had a renter with two children, a divorced man. In a fit of compassion he allowed his crazy ex-wife to move into the house he rents from me. Never put her on the lease etc. Things go sour between my renter and his ex (surprise). Cops are getting called, he wants her OUT of his residence etc. He calls me about it. I call the police about it. Police explain to me that because my renter moved this woman into the house, she now has legal rights as a resident. My renter cannot evict her nor compel her to move; I cannot evict just her, I have to evict ALL residents and the cops are basically playing attorney, judge and jury (which I explained to them and which they did not seem to appreciate my mentioning).
So I called back my renter and explained that the only recourse I had as the landlord in the matter (SINCE THE POLICE HAD TAKEN THE WOMAN'S SIDE WITHOUT ANY DUE PROCESS WHATSOEVER) was to file for eviction of the whole household for lease violation (moving someone in without owner's written authorization) and then I could rent my renter (a 6 year renter who always pays in full on time and has been a great renter other than this little episode) another house across town which was open.
The house in question is a great house right across from the high school where the renter's sons attend. He did not want to have to move. So he worked with his ex-in laws (her parents), his kids (her children) to convince her to move or otherwise her children were going to be displaced from their home of 6 years. She finally relented and agreed to move out and in with her parents (who didn't want her either but also didn't want to see their grandchildren uprooted over something dumb.)
So in the end the crisis was averted after MUCH consternation. My renter has gone back to being a great low profile renter who pays on time and he seems to have learned not to do THAT again.
My point is, don't end up in the position that my renter put himself into. This is a woman who is already trying to control you through these tactics. It WILL get worse, and it might be very difficult to remove her from your abode once you move her in.
Use
@Reykhel advice to further evaluate her if you see fit,
but put off the cohabitation. I see WAY too many risks to you under the circumstances. If she gives you an ultimatum as a result of you putting off moving her in, that is a huge power play you need to see in advance, and in my opinion worth dumping over.
Do not be blinded by whatever sexual enticements she dangles before you. This is exactly how you end up a beaten down man. Do not become that guy. Good luck with it.