Congratulations on your first flight, PWB!
You see all kinds of people here asking for tips on flying for the first time, and lots of them want their first plane to be something "cool" like a 'stang, or a corsair, or a giles/yak/cap, and you hear us all telling them that they'll likely snap it in in seconds, right?
Well, your plane just saved you from that! That "squirmy, mushy" feeling on slow take-offs is a result of the plane trying to plow itself some altitude at what is effectively stall speed. Sort of a harrier take-off. If you'd been flying any of the planes I just mentioned, instead of a proper trainer, the stall would have been much more pronounced, and you'd have a bag of splinters!
Try to make your take-off runs as long as possible. Ease the throttle on (take 3-5 seconds to roll it all in), and allow the plane to accelerate. If it's a trike, leave the elevator alone! If it's a taildragger, you'll have to "fly the tail" a while. Be ready on the rudder to keep'er on line. When the plane is at a comfortable flying speed, you'll know it! The slightest bump will have 'er airborne. Actually, many trainers will simply take off by themselves at this point. Then a real nice, pretty and scale-like climb out will result, and you'll be looking like a pro!
You'll look even more like a pro on your "second" plane, likely a more capable and demanding mistress, when you apply the same technique.
Congrats again, you're gonna be broke for a long time as a result of this!
J