How do I play my Necromancer? Confused..

[sinnedam]

So I just turned level 8, went and bought my spells and looked on the wiki to see what they did. I noticed 2 things.

1. it seems like my pet gets gradually weaker each time i get a new one. Towards the end game it looks like my pet is close to 10 levels lower than I will be..i dont understand how this can be effective. The way im soloing right now, I let my pet tank and throw DOT's at the mob. My pet at level 8 has a chance to be level 7-9 I believe, so he is still pretty strong with me at level 8.

2. I didnt get new DOT's this time around, so im not doing more damage, only 5 per tick. This was fine at level 4 when I got them but now at level 8 it doesnt seem like its doing much damage.

How are necros supposed to be played? Am I missing something or is my character going to be really weak as the game progresses. I just dont want to play a long time with this character if its going to be crap later on.

Thanks for helping a newb.