Yarn size

Hi
I started knitting a pattern for baby sweater,i casted on for 39 sts for a 6 months baby according to the pattern,i started from the top and one sleeve,but I found out that the size of this sweater is too much small,the yarn i used is 3.53 oz. I don’t know if relates to my yarn size or not?
If it does relate to the yarn size,how many sts should I cast on for a 6 months baby and how would the pattern change? Thanks alot
Rows 1-4: Knit
Row 5: Knit 3, Purl to last 3 sts, Knit 3 (Always knit first and last 3 sts. even on a purl row)
Row 6: K3, * increase 1 in next st, K1, repeat from * to last 4 sts, ending with incr. 1, K3 (56 sts.)
Row 7: K3, P to last 3 sts, K3
Rows 8 & 9: Knit
Row 10: K3, * inc. 1 in next st, K2, repeat from *, ending with incr. 1, K4 (73 sts)
Row 11: K3, P to last 3, K3
Rows 12 & 13: Knit
Row 14: K 4, *increase in next st, K3, repeat from * to last 5 sts, ending with incr. 1, K4 (90 sts)
Row 15: K3, P to last 3, K3
Rows 16 & 17: Knit
Row 18: K4, *increase in next st, K4, repeat from * to last 6 sts., ending with an inc. 1, K5 (107 sts)
Row 19: K3, P to last 3 sts, K3
Rows 20 & 21: Knit
Row 22: K5 *increase in next st, K5, repeat from * to the end of the row. (124 sts)
Row 23: K3, P to last 3 sts, K3
Rows 24 & 25: Knit
Row 26: You will now be placing markers to show the fronts, back, and sleeves
K7, M1, K6, M1, K6, M1, K1, place marker (23 sts for front)
K1, M1, K7, M1, K6, M1, K7, M1, K2, place marker (27 sts for sleeve)
K2, M1, (K7, M1) twice, K6, M1, (K7, M1) twice, K2, place marker (44 sts for back)
K1, M1, K7, M1, K6, M1, K7, M1, K2, place marker, (27 sts for other sleeve)
K1, M1, K6, M1, K6, M1, K7 (23 sts for other front)
Row 27: K3, P to last 3 sts, K3
Row 28: Knit across the row, increasing 1 st before and after each marker. (150 sts)
Row 29: K3, P to last 3 sts, K3
Row 30: Same as Row 28 (158 sts)
Row 31: K3, P to last 3, K3
You are now finished with the yoke and will begin work the sleeves and then the body of the sweater.
Knit to the first marker (25 sts) and place those stitches on a holder. Pull the yarn tight to avoid a hole in
the armpit of the sweater. Cast on 2 stitches using the backward loop cast on, knit across to the next
marker (31 sts), and cast on two more stitches. These 35 sts will be the first sleeve. Using another set of
needles (I used two of my DPN’s with rubber bands on one end), work these 35 sts in stockinette stitch
for 26 rows.
Sleeve Decrease Row: K2, (K2 tog, K3) 5 times, K2 tog, K2, K2 tog, K2 (28 sts left)
Work in stockinette stitch for 6 more rows.
Knit 4 rows.
You may choose to knit more or fewer rows at the end of your sleeve depending on how wide you want
the garter stitch edge of the sleeve to be. I knit four rows so that it would match the width of the neck
edge.
Bind off leaving the last stitch on the needle. With right sides together, sew the sleeve closed being
careful to close all of the holes at the underarm. Place the last stitch on the left hand needle. Knit 2 tog
and knit across the back of the sweater to the next marker. Place the stitches for the back of the sweater
on a holder.
Work the second sleeve the same as the first. Don’t forget to Cast on 2 stitches at each side of the
sleeve! When the second sleeve is complete, Knit across the remaining stitches (the other front side of
the sweater).
Slip the stitches on holders and the stitches you just knit (Body Row 1) onto a needle and work the body
of the sweater.
Body Row 2: K3, P to last 3 sts, K3
Body Row 3: Knit
Body Row 4: K3, P to last 3 sts, K3
Body Rows 5-26: repeat Body Rows 3 and 4 (you may alter the number of rows depending on how
longyou want the sweater to be.)
Work 6 rows in garter stitch. (Again, you may want more or fewer rows of garter stitch depending on how
wide you want this border to be.)
Bind off.

Hi and welcome to KnittingHelp!
What pattern are you doing? Can you give us a pattern name or a link and also the name of the yarn you’re using?
The best way to judge yarn for a pattern is to look at the gauge given in the pattern and compare it to the gauge of your yarn. Even better is to look at the gauge you’re getting with the yarn on your needles.
Best to edit your post to remove the pattern directions. We get into problems with copyrights when whole patterns are copied on the website.

Thanks for the answer and sorry for copy.
The name of pattern is five hours knitting pattern for baby sweater and the name of yarn is alize

There are a couple of versions of this sweater but maybe this one:


Alize seems to be the name of the manufacturer. There are many yarns of different weights. Do you know which Alize yarn you have?
http://www.ravelry.com/yarns/search#sort=best&query=alize

Thank you for your reply.
the weight is 3.53 oz,350 yds ,

The closest I found was the Alize Cotton Gold at 360yds and 3.53oz. It’s a sport weight yarn (26sts/4inches) and the pattern I linked to above looks like it wants a worsted weight (20sts/4inches).
You could try knitting a gauge swatch in stockinette stitch to see what gauge you get but that’s quite a difference in yarn weights. Because of all the increases and decreases, it’s not an easy pattern to modify. You would be better off to get the yarn used in the pattern, a worsted weight or even the heavier aran weight.
This version of the pattern is for 0-6months size and will work with the heavier yarn.