Puppies want to chew everything and love generating excitement in you more than anything. Chewing and attention are puppy catnip to her! The attention, the excited or forceful words that you exhibit pulling her off the pants' leg, the laughing or grousing, etc., and dealing with her as she dives back to grab over and over is just exactly what she feeds on - excitement, attention, involvement. The thing I always do to teach a puppy that grabbing onto clothing or the leash when walking is actually no fun is to just stop and look away, saying nothing. Don't react, look down at her or speak. Just stop, look away and wait until she loses interest in chewing on the pants legs (which I would lose and wear cut-offs or something). But go stock-still and wait her out, looking away, boring as all get out. Become a silent post standing there!
When she finally discovers you are no longer playing this game, she will start to lose interest. It will teach her a valuable lesson that when she grabs something she's not supposed to, all the fun and forward motion and excitement of going "walkies" just stops. It will take time in a young one for this message to get through but given enough time, it will. Once she's stopped inappropriate behavior, start walking agin and stop and freeze the moment she begins her antics of any kind.
One thing I like to do for a couple of days to keep a young, playful puppy's attention off me or my clothing or feet or the leash is to toss a little kibble tidbit ahead on the sidewalk to keep her brain going forward, not looking to the side and my feet or clothes. This tends to teach them to look ahead as there might be something interesting just ahead. For now, don't worry about her pulling ahead - you just want to redirect her for a bit to thinking of what's ahead and not what's on mommie or daddy's ankles. Once she's learned to look ahead on leash, away from your feet, and learned you stop dead still if she does attack your feet or clothes and that's no fun, she'll be into pulling on the leash for fun.
Now you progress to the next problem - pulling on the leash. Do the same with pulling forward on the leash that you did when she attacked your clothes - the moment the leash goes taut from her pulling, stop until it's relaxed and then start to walk forward until it goes taut again, stop again until she stops pulling. Start, walk, she pulls, you stop & wait until she stops pulling. That's how it goes for a while until she gets it. Of course, don't add excitement to the process by talking and I don't spray them with water or aerosol as to my thinking, that just rushes adrenaline into the system in a lot of pups. With some, it might work okay but with those I've trained, they tend to startle and get all adrenaline rushed & then confused when I don't want them jumping around from the rush. Some back off and act intimidated. But go with whatever is positive and doesn't hurt or scare and works best for you and your dog.
When they are this young that they just want to play on walks, I like to keep the walks short but more frequent - 3 or 4 a day very short ones. And you can keep your good humor better if the sessions are short.
Walking a puppy can be challenging but keep it fun, light, positive and above all, loving, & she will learn as they all do.