Is it worth the trouble trying to see the Northern Lights if your travel days are not flexible? We would be going in February 2026 mid month during the dark moon. I know weather and solar activity are unpredictable. We could probably allot 2-3 days. I'm reading about the Snaefelsnes peninsula as being a good place, but it's 2 hours from Reykjavik. Hveragerdi is only 42 minutes.
Don’t worry about going anywhere, just look up. If the aurora is not strong then an area with fewer lights will make it easier to see but you don’t need to go far. Even just 15 minutes away.
FWIW February can be tough as weather is notoriously bad in February. Two of our trips were then and both times we had full on blizzards. On one of those trips though we did see the aurora upon landing.
You might consider a tour. I personally like Aurora Experts and we have used him several times. He won’t go if there is not a decent chance of seeing the lights, which is much more ethical than some other tour operators. He also gives a second chance. We are booking with him again for early March.