Don't worry 1stbaby - everyone feels like this to one degree or another before they go back to work. I was exactly the same, but it's amazing how quickly you adapt to the new arrangements.
If you like this childminder, then she is almost certainly lovely. Your instincts are strong things. And DD will have a lovely time with her, and do lots of things she might not do at home, and although for the first year it's good to be the Mummy-daughter team, it will be good for her to socialise with other children and learn to be somewhere else. But you MUST be calm and happy about leaving her, or she'll pick up on your anxiety.
(And if you find your CM doesn't work out, you can get a different one - these decisions are not final)
As for your career - it sounds like you really enjoy your job, and that's allowed! You are not a selfish cow. I found once I went back I really enjoyed having time where I was just me again, and not a mummy - it made me much happier and more able to be a good mummy when I was with DS.
Is there any way your employer would let you do a phased return? Start on three days a week for a month, and then work up to full time? It might help with the anxiety and getting everyone settled into the new arrangements.
But honestly, don't worry too much - you'll be amazed at how it all falls into place once you start, and you know what, if it doesn't - then you can stop! Nothing is irreversible.
HTH