SO CONFUSED (from a skinny-fat gal)

Hi everyone

ok here's the deal:
im female ,height: 5'3 weight: 116.6 pounds age: 17

i have been counting calories at a deficit for about a month now (netting around 1350-1500) but i decided i dont want to lose any more weight but instead want to build some muscle and strength (bc i have none). i think i am what most would describe as skinny-fat bc i am a healthy weight but i still have some flab/my body is quite soft. my goal is to gain some muscle and definition and just generally get a harder body...if that makes sense

this girl isnt me but this is kind of what im going for http://24.media.tumblr.com/3163b09582eeaeb2e714aac82859f72d/tumblr_mh57w5HNVa1s3wcjqo1_500.jpg
http://25.media.tumblr.com/7714b3c80900f763ed5f3de203fe380a/tumblr_mhtw7w3oWy1s3wcjqo1_500.jpg
http://25.media.tumblr.com/9532b707e35464b3155ca240df4091cc/tumblr_mknfkalozm1s3wcjqo1_500.jpg

to me it looks like she managed to gain some muslce while losing body fat? i could be wrong but my main problem is idk how much i am supposed to be eating. if i NET at my maintenance (around 1600-1800) work out at least 3x a week (i can go to a gym which offers circuit classes and has dumbells plus a pull up bar) will i see any results? im just not sure how much im supposed to eat as a TEENAGE GIRL looking to build a little muscle but not get fat (obvs). i dont mind counting calories but i want to know i am getting the right amount and im just so confused by all the contradicting info out there :S

im not completely inactive (i do general cardio and some strength) but i want to get into a proper routine for summer and hopefully build some strength and "tone up" (which i know is bull**** btw haha)

if anyone has any ideas of how many calories a teenage girl who is starting strength training should NET please let me know!

THANK YOU