Below is some reasons why you may not find your images found in Google images index
Check your robots.txt and ensure you do not have
Disallow: /*.jpg$ as this would definitely stop your images appearing in Google image search.
Ensure that your image is unique, duplicate images are detected by Google all the time and it's useless to show the same picture on 1 million plus keywords.
Google image search is far from real time and much slower than normal SERP, it can take many weeks to months for images to start appearing.
Things that you can do whilst you wait
Reduce the size of the logo
Reduce your JPEG using a lossless compress or preferably use PNG as your logo as this does not use compression that reduces the quality combined with a PNG lossless compression.
Improve your markup
While its not essential good markup does help Google associate your content. Below is what you could use instead for your markup to give Google more indications that its your logo:
<div itemscope itemtype="http://schema.org/Organization">
<a href="http://site.com/" itemprop="url">
<img src="http://site.com/your-logo.png" itemprop="logo">
With the above code you should ensure that your pathnames are absolute and not
/ without the full domain name, I'm not ensure why but this is how schema suggests it should be done, also if your not to fussed about having good accessibility for blind users then you don't need the alt tag with your company name as the schema tells search engines that's your logo. Also its not essential to include the term logo in the ALT unless you want users finding it with that exact term, ideally you want the image coming up just with your site name or business name.