I hope this the puzzle pieces are going to start falling into place. The most logical thing would have been for SM to go to HE's apartment and have her take the test there. But it doesn't appear that happened, so he HAD to have taken her somewhere in his truck. But why would she have agreed to meet him at PTL to take a pregnancy test??
I was looking at the timeline thread and after he purchased the pregnancy test, he made the call to Heather from the payphone, then went home:
Wednesday, December 18, 2013:
1:19 AM surveillance footage of SM buying pregnancy test at Walmart. Paid with cash.
~1:30 -1:35 am – SS dropped HE off at her apartment, said she didn't answer any calls during their date, she was in a good mood but tired, not crying or upset
1:35 am – HE receives a call from SM; call was placed from a payphone & lasts 4.83 minutes
1:44 am – From her apartment, Heather called her roommate BW, who was in Florida, and spoke for 2.2 minutes; was crying and upset after the call from SM because she was trying to get her life back together after her affair with him and harassment by TM.
1:53 – 2:09 am – 10 posts are made to HE’s Tumblr account Ten posts
2:29am: Heather tried to call SM back at the pay phone number several times, but no one answered
3:16am: Heather tried to call SM's cell phone, no answer
3:17am: Heather called SM's cell phone and spoke with someone for 4.15 minutes; (Phone pings place HE’s phone at her house & SM’s phone at his house)
~3:21 am – HE drives to Peachtree Landing @ 6699 State Rd S-26-611
3:36am: A security camera at a private residence 1.7 miles from the M home recorded a distinctive late-model Ford F150 coming from that direction and heading toward Peachtree Landing
3:38-3:39am: Heather had arrived at Peachtree Landing and tried to call SM's cell phone four times, but there was no answer
3:39am: A security camera at a business 1.2 miles from Peachtree Landing recorded the Ford F150 heading toward the landing
3:41am: All data and GPS signals ended on Heather's phone
3:45am: The security camera at the same business location recorded the Ford F150 returning from the direction of Peachtree Landing
3:46am: The security camera at the same private residence recorded the Ford F150 returning from the direction of Peachtree Landing toward the M home