Mickey 123, it is very difficult to say how heavy a pup should be and yes they grow very fast. I go by logic and I am sure I shall be shot down by other forum members. I like to keep my pups lean and mean as this will be less stress on developing joints. Stop them from running on slippery surfaces, no climbing stairs and no standing on their hinds. Do note, a total amount of food consumed daily is more or equilvalent to a big dog. You will have to decide what is the right weight. In future get a pup from a proper breeder and you will be surprise to find there are breeders that are interested in finding a good home for their pups than making money.
oh my god.. she does everything that you mentioned!!! cause I let her stay in the house but, sleeps in the crate at night. Since my house is marble floor, it's quite slippery.. how to stop her from running on the slippery surface? cause when she got excited, she'll run very fast around the house.. can't stop her at all!

now she likes to jump on people's back when we sit down on the floor.. we hate this, but, don't know how to stop her?
actually, when the breeder heard that we love this puppy so much, she's very happy..
it's not really that big of a deal as long as your pup does not OVER-DO it. it's just being a pup playing. but the jumping on people's back part, yea you'll definately need to teach that is a big no-no. or else in the future your pup will love to jump on you. whether it's alright to do so at that moment, your pup will not know. to her, eveyrtime is a good time to jump. you'll need to enforce the rules for your pup not to jump. mine was jumping a ton when he got here. but he's learnt that if he jumps when he's not told to (ie. jump or up), he's not allowed to jump. Used to jump a lot when I prepared his food. So for me, that's the best time to teach, during food lol. they'll do anything for food. For me, my pup needs to learn to say please when he wants something, so, when he jumps = no food. When he sits = food. Quite a fast learner when food is in jeapordy
as for slippery surfaces there MIGHT be problems but for my mom's and sis's maltese they have not had any joint problems. think the reason PSY is trying to say, due to the slippery surfaces, your pup will need to strain the mucles/joints more to stand up or walk etc. as for the standing on hinds, well just don't over-do it. they are pups :D stopping them from doing what they want now, might emphasize to them they are NOT allowed to stand on two feets etc. so don't make a big deal out of it. just let them have fun, but control the amount of play-time and stress they put on themselves. when she wants to rest, let her, don't go poking her, or trying to move her etc. if she really wants to rest, immediately let her do it in a quiet place or somewher you know she can really rest. pups needs their sleep just as much.
psy also mentioned that keep an eye on their food in-take. not much argument there but there are owners that feels you should allow the puppy to eat all they want until they are full etc. so it's really up to you. for myself i'll let the pup eat the "recommended" amount for his/her weight of kibbles, BUT I only allow a good 15 minutes. AFter 15 minutes i'll take whatever is left in the bowl. first reason, should not leave any food in the bowl to begin with as your pup might develop a bad habit of not eating when she's supposed to cause food is ALWAYS available. Reason two, food will get stale and god knows what insects or stuff might get into the food and causing your pup to get sick.
usually joint problems can be seen in bigger breeds, and owners who feeds them food that boosts their growth. Their size grows but their bones and joints does not develop in proportion with the weight. that's when joint problems will occur. But if you really watch your pup's intake, making sure she gets all the balance nutrition she should be fine. What PSY said do have it's truth in it which I agree, but limiting what a pup does best (play) is almost just as bad as not giving them their required nutrients.
So play with the pup, but while it's young, keep the play sessions mild and short. As she grows you can increase the duration. keep food intake good and balanced. Be cautious but not overly worry-some mother. most importantly enjoy every moment with your furkid!
*rant off*
thanks for telling me in details, I learnt a lot from you.. I'll try to control her jumping during her feeding time.. ;) actually, she loves food, hahahah.. so, she won't left any food behind.. ahahhaa.. which is good.. :)
about running around: I think the only thing I can control is her weight.. hope that by doing this, will reduce her risk on getting the joints problem..
about the playing time: she'll play until she's tired and she'll get into the crate by herself to rest.. very cute.. but, if I force her in(normally is when I have work to do), she'll bark at me.. by the way, she'll stop it when she finds out that I won't let her out even if she barks at me..