I'd vote for Meghan. It is similar to your old name, which will make it easier for people to adjust. It might be easy to adapt your signature, too.
My birth name was Keith. I chose Kathy (Kathleen) because of the similarity. I sign documents as "Kathy", so my signature felt totally natural the first time I tried it. I have heard people start to dead-name me and then switch to the right name, and I was probably the only person who noticed. I have heard Ke-yathy and Ke-Kathy. Works for me.
Kathy is a common name, or was in my generation. I like that it is age-appropriate. But I also like that it feels simple - common if you like. I couldn't see me as an Amanda or Monique. I'm a down-to-earth girl, and Kathy is a down-to-earth name.
I chose my middle name on the same basis: Lawrence -> Lauren. I had less concerns about ease of use or signing, since I seldom use it. And Lauren Bacall was a popular movie actress about the time I was born, so it is very plausible as an age-appropriate name.