choosing right tippet size

im just gettin into flyfishing, i went the other day and hooked 4 fish, lost all 4, all broke at the tippet knot or tippet to fly knot, i have 4lb test on my spinning rod and it never broke even with large steelhead, im using 7x, is this too light, can i get away with 3x or 4x, fishing meadow run and dunbar and other local streams

The tippet size your using for steelhead - 7x is way too light. Depending on what type of tippet material your using it is probably rated at only 2 - 2.5 lb test. The only time I use 7x is when I'm casting to extremely wary trout - in low clear water during the summer. For steelhead I always use 3 - 4 x which is rated at 6 - 8 lb test, again depending on what brand your using. I also use flourocarbon. As for the knot, I learned to use the improved clinch knot and have never had this knot fail. Hope this helps.

There are a few things to consider when you're choosing what tippet to attach.
 
The thinner in diameter that the tippet is, the harder it gets to turn over larger flies and shot. If you are casting small dryflies in very clear water, 7x is fine. If you are casting a larger dry. lets say a size 14 adams, your tippet will have trouble casting the fly, and your leader will likely twist while your casting. With nymphs, I typically never use anything less than 5x, unless low and clear conditions call for it.
 
For steelhead, since your most often using nymphs, eggs etc, with some shot, I wouldn't reccommend using anything lighter than 5x, because anything lighter would not turn over well, and because steelies will break anything less with ease.
 
I dont often pay close attention to the pound test rating on tippets. A lot of the tippet materials such a frog hair have a high pound test rating, but dont hold a strong knot. Other materials like maxima have a lower pound test rating, but hold a very stong knot.
 
As far as matching tippet strenth to the size and fight of the fish, just use common sense. If you keep breaking fish off, try heavier tippet, or check your knots.

i know my knots are strong, i just think the 7x was too light for where i was, im gonna pick up some 4 or 5x and see how that works

I most often use 5X for trout and 3X for steelhead.  The original clinch is much stronger than the improved (if I'm thinking of the correct knots).

ORIGINAL: TransAmWS6

 can i get away with 3x or 4x, fishing meadow run and dunbar and other local streams

 
Probably 4x and 5x for trout in those cricks.
6x if you're fishing tiny flies.