My first lot were sown at about the same time as yours and were slow but are now a couple of inches high. Second lot were about a month later and are just showing (with gaps but I always get gaps with carrots, however thickly I sow). I saved a whole load of sunflower seeds last year from my most beautiful flower and planted loads of them. I thought they were taking a long time to come up until I realised the crows were nipping them off. They've also pulled up and chewed every single sweetcorn plant (40 in total) and most of the pumpkins, squashes and gourds. My best ever plants, sturdy looking creatures, in the middle of the chicken run so safe from the badger and slugs (and fenced from the chickens and ducks). So instead the crows have ruined the lot. Had somebody over yesterday to shoot them but they're canny and he only managed one. I've hung it up in triumph and so far they're steering clear and the chicken food seems to be going a lot further! Sorry, that was a bit of diversion into crow rant.