Running and weight loss...or lack of...
Nickie, as you know, I have the same issue, even though I'm a beginning runner. Here's a thought on that topic. Do you wear a heart rate monitor? If so, read on! I use one which links with Endomondo to tell me how much time I'm spending in specific heart rate zones. For me, my resting heart rate is 63, and max is 171 (I'm 52), so here are my numbers just as a reference:
1. Resting (63-117)
2. Warm Up (118-126)
3. Fat Burning (127-138)
4. Aerobic (139-148)
5. Anaerobic (149-160)
6. Maximum (161-171)
"The body does burn a higher percentage of calories from fat in the fat burning zone or at lower intensities. However, at higher intensities (70-90% of your maximum heart rate), you burn a greater number of overall calories, which is what matters when it comes to losing weight."
The same article says that shorter, high intensity workouts and / or interval training should be a staple of a good training plan along with endurance workouts if your goal is to lose weight.
A lot of scientific mumbo jumbo that says keep on doing what you're doing! I think you have less fat to burn, therefore it doesn't seem like you're losing weight. Good luck on that half marathon!