.NET OR SQL developer

Switching company in so less time span is not good. 
There are some big enterprises who look average working period of 1-2yrs per company. They take your total work years and divide it with how many companies you have worked in this period. This figure should be about 1.5yrs.

But again, if someone is in need of a resource and you fit in skill sets and other stuffs, they will not see/check this.

Believe me the best decision would be yours!!! 
Because you can understand better than others about the technology understanding and interest. And don't worry about the current understanding level on a technology if you have more interest in it and more important point : if it is going to rock in future.

But let me give you some idea according to my understanding of IT market. 
First and foremost, you have knowledge of Business Intelligence with ASP.net controls that sound good for your career. If you enjoy working with SQL, keep this track as SSRS, SSIS .... This is very good.

As per your given details, I realize you are bit far from current technologies trends like WCF, MVC, Sharepoint, Silverlight etc. So you will require to enhance your skills on these current technologies.

Better I would like to suggest you to go for data analysis skills in SQL. You can go through with Data warehousing, Data mining(used in future forecasting), OLAP and other advance skills. Believe me these will require very less time to grasp your understanding and also have very good demand in market. Your current .net skill set will be advantage over it.

But again, let me say it is upto your interest what you like more!!!!