Ingrid, I think your sweater is just lovely! I'm a big fan of machine-sewn steeks, but I know lots of folks share your hesitation about them. I did, too, until a friend showed me the ropes. So, I thought I'd mention a few favorite points of mine, in the interest of spreading some steek-love:
1 Machine steeks are always less bulky than crocheted steeks. Who needs extra bulk?!?!?
2 As you mentioned, crocheted steeks are really safe only on very sticky wool (read: Shetland wool). But,
machine steeks can be beautiful - and extra secure - on anything, including Shetland wool.
4 You don't have to be a phenomenal machine sewer to get a phenomenal machine-reinforced steek. In fact, you can be quite the novice and still get a fine result! Use two lines of small, straight (as in not zig-zag) stitches (like Ingrid - good girl!) and as long as you keep them away from the actual body stitches, it won't matter if you're a bit wobbly - they'll never show.
4 Use common scotch tape to tame loose yarn ends (on the WS) so that they don't snag in your machine.
5 Put cardboard between the layers for worry-free cutting.
6 Relax - it's fun!