Jakki, with no disrespect intended, if you genuinely loved your partner you wouldn't be asking these types of questions. Having doubts about a relationship is normal, however continually second-guessing your relationship when there is obviously a lack of trust and commitment should be worth raising a warning flag.
To answer your question, there is no preset timeline that determines when you should be falling in love with someone, you simply know when it's happening; that doesn't mean that both partners shouldn't proceed with caution if they aren't well familiar with each other.