Can low testosterone cause anxiety and sleeping problem?

Hi,

I'm a 27 year old Asian male.  I'm 5'7 and 145lb.  

I have been suffering from Anxiety since 7/2006.  My anxiety happened suddenly and I have a hard time falling asleep.  I was a very skinny person but I gained like 30 lbs in a month (from 135lb to 165lb) when all the problems happened.

I have seen many psychiatrists and tried all sorts of antidepressant and anti anxiety medications such as xanax.  They don't help much.

In 3/2010 (I was 26 at that time), I had a blood test for testosterone.  I check for that because I never have any mustache, my muscle do not grow and I have a big belly.  I'm tired all the time also.  Here are the results (morning blood test):

Testosterone (total): 238ng/dL
Albumin: 4.7g/dL
SHBG: 17.6nmol/L

Several other blood tests shows my testosterone to be between 210 to 240 ng/dL

The doctor said my testosterone is just borderline low and refused to give me medication.  I talked to 3 endocrinologists and finally one endocrinologist prescribed me androgel 1% 5g to use everyday.

I noticed my sleep, anxiety and energy level is a bit better; however, I still feel anxious all the time and low energy.

All the endocrinologists told me testosterone has nothing to do with anxiety and sleeping.  Are they actually correct?  The reason I ask is that I feel slightly better after using the testosterone gel.

After I use the androgel 1% 5g everyday for several months, I had another blood test for testosterone.  The result is 549ng/dL.  Is this a good number for a 27 year old male?

Do you think I have enough testosterone?  
Can my anxiety and sleeping problem from low testosterone?  I ask this because I really have nothing big to worry about.