6 weeks is usually long enough to know if a dose is adequate. Adding another 25mcg seems quite reasonable.
Do you have your blood test results with referernce ranges? If so, please post them here so we can see if they can tell us anything.
Quite often doctors stop increasing the dose once the TSH comes into the normal range but this normal range is merely a statistical distribution of a group of people and is quite a wide range. In fact, the distribution is skewed and the median is around 1 which means that most people actually are well with a TSH nearer to 1. If yours is much higher than this, you probably aren't on enough levothyroxine yet. Having said that, the TSH measurement isn't particularly helpful once you are on thyroid hormones like thyroxine anyway. The t4 distribution shows most healthy people have a t4 in the upper half of the range but again, this is likely to need to be higher if you are taking levothyroxine. Your doctor really needs to go by how you feel.
Your symptoms definitely sound like those of hypothyroidism so it sounds like you needed that extra 25mcg and possibly more in the future. 6 weeks is a good amount of time before increasing your dose.
I hope that helps to reassure you.