Recreational / Hobbyist UAS pilot was flying near the edge of their approved airspace authorization. Flight was completed safely. During the post-flight the pilot learned they did fly outside of their authorized airspace.

Narrative

Planned recreational video shoot a few miles from ZZZ. Wanted 400 ft. height to be able to see all the way to downtown and possibly departing aircraft passing in between location and downtown but also knew about airspace authorizations and wanted to do it safely and legally. Used AirMap app (application) to find an appropriate place with possibility of 400 ft. LAANC (Low Altitude Authorization and Notification Capability) authorization. Picked recreation area to operate; which is within a 400 ft. LAANC 'square' on the AirMap app; created a flight request for 15 minutes in the future and lasting 45 minutes. Received approval to 400 ft. so I got ready to drive to the location and loaded up [my] kids to come along. I figured this was fine because they like helping with drone stuff and we were going to be at a recreation area with a nice playground----so if they tired of watching and helping; they could play on the playground. And my LAANC approval was a rectangle drawn in AirMap that more or less covered the whole recreation area. I intended to launch from the middle of this square near the playground to leave a nice buffer in all directions.Upon arrival at the recreation area; we found the whole recreation area fenced and therefore had to park on the south side of the recreation area where there is an unfenced side yard. This put us right on the edge of the authorized airspace that was requested through AirMap LAANC app.I didn't check the AirMap app upon arrival because in my mind I had requested and received authorization for the whole recreation area. I ended up launching right from the edge of my approved area which in my mind was fine because I was approved for that. Spend 15 minutes in the air; more or less directly overhead the launch point though I did at some point realize I was kind of close to the edge of my approved area and then I did fly 30-50 ft. further toward the middle of the recreation area and the center of the area I was approved for.Upon packing up; I went into AirMap to cancel my airspace authorization early and realized that my launch point might actually have been 5-20 ft. outside of the authorized area; and that this area was immediately adjoining a square in the app that only allowed automated 100 ft. LAANC requests. I may even have gone above 100 ft. before realizing I was close to the edge of my authorized area and intentionally ensuring I was situated well within the requested & authorized area. I don't believe this caused any sort of safety concern; but I believe there's a 50-75% chance I launched from right outside my authorized area; and a 25% chance that I went above 100 ft. within a quadrant on the map where only 100 ft. LAANC authorizations are allowed (but the UAV (Unmanned Aerial Vehicle) was likely only 10-30 ft. outside of the authorized area where 400 ft. was approved).LAANC apps like AirMap allow for advance request of authorization; but it should really be part of my pre-flight check to look at the app immediately prior to launching instead of relying on my memory of what airspace I requested in advance and was authorized for. Perhaps the AirMap app and other LAANC apps should do a push reminder to your phone at the start of the authorized time that reminds you to open the app and make sure you are indeed operating within the authorized area. I could have made an even bigger mistake if I had driven to the wrong recreation area and just relied on my memory of where I had requested and received authorization. The advance authorization request option is critical to planning but it comes with this potential downside/risk relative to making an airspace request once you've picked a spot and are about to launch. Human factors: Bringing kids along caused me to be a bit more rushed with launch especially because we were trying to be there only a short time before heading home for dinner. Also; their disappointment with the locked gate at the recreation area was probably a distraction. Ibelieve there is a way for the AirMap phone app to talk to [the manufacturer] drones and remind you mid flight if you are straying out of your authorized area. I've never figured this out; and it's not immediately obvious how this works so I never found time to fiddle with this and get it working. I need to do the hard work of figuring this out before flying again in an area that requires LAANC authorization.[The Manufacturer] app is good at forcing you to very consciously go through a number of hoops in order to take off in Class B surface airspace. You cannot do it accidentally. If only it would also talk to LAANC apps (or have built-in LAANC capabilities) and import an outline of the authorized area into the app to remind the operator during the flight where they are authorized for.