I have the nagging feeling that after she left the hotel at 6:05am, she drove to St. Michael's Church in West Memphis (170 mi, about 3 hr drive with no stops) to attend the 10:30am Sunday service. Before the service she confides in a priest or someone else connected to the church (maybe someone linked to that priest she follows on YouTube who seems to be based in London), then the service ends around 12:15pm. She leaves ~12:30pm and drives the 90 miles to Hazen, placing her there around 2pm -- 8 hours after departing the hotel.
I think she was trying to decide what to do. Whatever she had planned to do in the direction of Hazen, she changed her mind and decided to head BACK to West Memphis. So after pacing around, maybe getting something to eat somewhere (paying cash), feeling very hazy and sleep-deprived & indecisive, she decides to return to West Memphis around 3:30, arriving at the gas station at 5pm. When she gets there, she makes the decision to ditch her phone and go into hiding with the assistance of someone from that church.
I think in the months leading up to her disappearance, some people close to her convinced her that her desire to convert from Baptist to Catholic was a symptom of mental illness and that a conversion was a very BAD thing. She was already depressed and struggling with that decision, and paired with insomnia that was going on for who knows how long, she was in a very fragile, vulnerable state of mind. She started to wonder if she really was crazy and needed help, so she told her husband she was going to go seek mental health help and stay with family for a while. But instead she made that trip to see someone at St Michael's church and she began to feel more confident in her decision to convert. This confidence led her to return there a second time and whatever happened during that 2nd visit convinced her to go off the grid while she figures out what to do.
What do others think? Is this just all crazy speculation? The timing lines up pretty well. Only problem is I don't know what took her toward Hazen.