Return to running after sprained ankle

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I apologize for asking this, because I know it has probably already been asked a hundred times... but I need help deciding how much is too much when returning to running after a sprained ankle.

I sprained my ankle three weeks ago. It was not an awful sprain, but it did swell/bruise and I limped for about two days. It is still swollen, but not that painful. I took up swimming throughout the three week recovery and returned to running on Wednesday at just two miles. When I ran, my ankle didn't really hurt; it just felt tired and weak after the first half mile (I kept going anyway). Of course, I am also icing as much as possible, taking NSAIDs, tracing the alphabet with my toes, etc. etc.

Before I sprained my ankle, I was running about 12 - 15 miles a week in preparation for my first half marathon in October. My long run distance was at 6 miles (comfortably). I REALLY want to recover and build up to complete the half marathon in 8 weeks. Is that realistic? If you were in my situation, what would your long run schedule look like each week?

Here is what I'm thinking:

Week 1 - 5 miles
Week 2 - 7 miles
Week 3 - 8 miles
Week 4 - 10 miles
Week 5 - 11 miles
Week 6 - 12 miles
Week 7 - 8 miles
Week 8 - Half Marathon

Please let me know if this is realistic, and whether or not you think I'm setting myself up for re-injury. Thanks!