The "normal" on this depends on what you read, and whose research you follow.

30 is not really "normal"...the new lowest normal is 50.

Doctors tend to go by the lab ranges printed on the results. So if that range says 30-100... that means you are normal according to it.

But for MSers, 30 is not really normal.

I think you should read the information on MS and Vit D.
example:
http://www.huffingtonpost.com/dr-dav..._b_818912.html

Your doctor is probably conservative. And does not want to take responsibility for you past the level you reached.

This will have to be your decision.
We have a D thread on vitamin forum:
http://neurotalk.psychcentral.com/thread92116.html

If you Google MS and Vit D there are many articles.
If you decide to increase slightly more to 50... watch your calcium intake. D increases calcium absorption and high dose calcium supplements are not really advised in patients with higher D readings.

the average rule is 1000IU D3 for each 10 pts your need to raise.
That works for most, but not all.