Take a moment to 'pause and breathe'!
Please try to understand that puppies (and young dogs) are fully packed with energy, and an innate drive to play a LOT. Many dogs retain their love to play with other dogs or us, right through their senior years, that is how they build and maintain muscle, flexibility, strong joints, learn to interact with each other in a dog appropriate way, and burn off that energy, it is perfectly normal dog behavior.
Take the time to consider whether you are providing other ways to help them burn some of their energy off, work their brains and their bodies, play with them one on one, do training sessions, teaching new skills, rehearsing the ones they have, teaching tricks with one, while the other is confined in a crate or x-pen with a good bone/chew toy or stuffed Kong to work on. Teach them to settle on a mat.
One thing to remember is that if we do not provide them with appropriate opportunities to use both their physical and mental energy, they will find ways to use that energy themselves. Dogs are not born with 'self control' but they can and do learn it over time, maturity/age plays a big part in this! there will be times when they want and need to play and there will be times when they are happy to just relax and enjoy some 'quieter' time.
I understand the desire for a lap dog, and more than likely that will come in time, as your puppy matures, and settles down some, but right now, life is a party and she wants to play and have fun - cuddle time is for when they are ready to settle and relax - perfectly normal for a puppy.
My border collie, still very much a puppy at 2 1/2 yrs. old, loves to play, lives to play, cuddle/snuggle time ( he loves to snuggle but on his own terms) happens when he has had enough exercise, and is ready to settle for a bit. When he is playing with our senior lab, or his friend from across the road, he has no interest in me, he wants to do what dogs love to do (and should be allowed to do) - play and have fun- and that is okay!! (I wouldn't take a child to a playground and expect them to sit on my lap) there is a time for play, (he has developed enough self control to wait until he is invited to play) and a time to chill out and relax, for them and for us.
Something to keep in mind is our 'expectations', sometimes we need to take a step back and really think about whether we are being realistic or are we expecting more from them than they are capable of giving/offering at this particular point in time?
I do understand your concern over the little one hurting herself, there is always a risk when puppies play together (and are learning to play appropriately) that they may get hurt, but in all honesty, it doesn't happen very often, puppies are incredibly 'tough', perhaps a chat with your vet about how much play is appropriate and safe for your tiny pup, would help to ease your mind.