Okay I am going to try and explain the best I can everything I can.

I have a 13 month old boy, who is 20 pounds and tall for his age. He is in 50th percentile for height and just over 5th for weight..right now we are still struggling with his eating as he is extremely picky, so he has dropped from 25th percentile for weight (which was at 9 months - it seems that he has become quite active and as yet is not gaining enough calories to gain good weight - the docs told me he is not in any danger or anything, just on the thin side, and that some babies are just like that. I personally would like to see him a little bigger and we are working on the calories and have started pediasure just as a supplement twice a day) to the 5th percentile, or just above that.

Anyways, he is still growing in height, im not sure exactly how much but everyone says he is tall. He is hitting milestones - he started walking last month. He can almost run now - although its clumsily(very cute too).

Now, the thing I am concerned about - and i do plan to ask the health nurse at our appointment but wanted input from you guys - is that he doesn't really even have one word yet. He does babble tons, and says what SOUNDS like ma-ma-ma-ma-ma and na-na-na-na-na(nana, I think?) Do these qualify as words, or is he just babbling? He has yet to say a concrete word though, and that worries me.

However, I am a very quiet person - I try to remember to talk as much as I can around him, but it really is not in my nature to talk alot and sometimes i find myself having been quiet for a good peice of time. As well, he has been a fairly quiet baby from even before he was born. This both worries me and reassures me...
Before he was born he was what they called "non responsive" a few times on ultrasound - he just didn't want to respond to being poked alot i think lol. He moved plenty, just not when YOU wanted him to... When he was born too he did cry, but not often. Even the nurses said what a good baby he was...Im not sure if that is because I am a very responsive mother(in that i respond to his needs as soon as they become apparent) and we are well bonded from the start(he nursed as soon as he was born!) or if thats indicative of an issue too. As he grew older, he still was not much of a crier or a cranky baby. He has been babbling since he learned it from my best friends little girl at age 4months. This is part of what concerns me, because you would think that if he babbled since then, he would be speaking by now.

As far as other milestones go, he hit everything physical and social early. He rolled over early, smiled early, laughed early,sat early and crawled early. So everything seems to be good on that end.

I just am concerned, because Im afraid that this not eating good plus the not talking thing(and actually, not waving yet or really giving kisses or throwing things etc) may be indicative of some type of Failure to thrive issues.. i cringe just saying that because it has such a bad stigma for parents whose children have it.. but i mean I cant force him to eat - he just spits it out..its very frustrating.

I do make sure to spend a while each day going over words with him - saying them slowly, repeating them etc.. he loves it, he laughs his head off.. but will not repeat. Maybe I should try cursing, LOL. Kids like to do things adults do maybe that will work - JUST KIDDING!!

We read books, usually 3-5 a day, sometimes more if hes having a cuddly day. We play together, although he doesnt often care to play WITH me - he will wander off and play with his toys by himself, coming back to me every so often for a cuddle, hug or sippy of milk.

Do you think im over analyzing? Or could there be a problem developing here. I will say i've seemingly been a worry wart before - I think I called the doctor everytime he looked at me crooked for the first six months LOL.
Additional Details

Edit: I realize this is really really long, and you do not have to read it all..just skim if you want. I just wanted to provide as much information as I could in case anyone had questions about anything