Begin crocheting from the top to bottom.
Make a foundation chain of 47 chains (I do not count one chain). One repeat between corners is 4 chains. To adjust the size, add one repeat/4chs to each shoulder part and back part.

1st row – h4ch, dc1, shell1, ch2, [(dc2 into 1ch) x 2, ch2] x 2, shell1, ch2, [(dc2 into 1ch) x 2, ch2] x 4, shell1, ch2, [(dc2 into 1ch) x 2, ch2] x 2, shell1, dc2 into 1ch + RC1
Mark your corners/shells.
2nd row and all even rows – h2ch, sc to end + RC2

3rd row – h3ch, dc1, dc2 into 1ch, dc1, dc2 into 1ch, ch1, dc2 into 1ch, dc10, dc2 into 1ch, ch1, dc2 into 1ch, dc18, dc2 into 1ch, ch1, dc2 into 1ch, dc10, dc2 into 1ch, ch1, dc2 into 1ch, dc1, (dc2 into 1ch) x 2 + RC1

5th row – h4ch, (dc2 into 1ch) x 2, sk2, (dc2 into 1ch) x 2, ch1, sk1, (dc2 into 1ch) x 2, sk2] x 3, (dc2 into 1ch) x 2, ch1, sk1, (dc2 into 1ch) x 2, sk2] x 5, (dc2 into 1ch) x 2, ch1, sk1, (dc2 into 1ch) x 2, sk2] x 3, (dc2 into 1ch) x 2, ch1, sk1, (dc2 into 1ch) x 2, sk2, (dc2 into 1ch) x 2, dc1 + RC1

7th row – h3ch, [dc to corner, Vst1 into corner] x 4, dc to last 1ch; dc2 into 1ch + RC1

9th row – h3ch, *sk2, [(dc2 into 1ch) x 2, sk2] to corner; shell1 into corner, repeat from * four times, sk2, [(dc2 into 1ch) x 2, sk2] to last 1ch; dc2 into 1ch + RC1

Use a larger size crochet hook to widen the garment.
11th row –h3ch, dc1, dc2 into 1ch, [dc to corner; (dc2 into 1ch, ch1, dc2 into 1ch) into corner above middle 2dc of shell] x 4, dc to last 2chs; (dc2 into 1ch) x 2 + RC1

13th row – h4ch, *[(dc2 into 1ch) x 2, sk2] to corner; (dc2 into 1ch) x 2, ch1, sk1, (dc2 into 1ch) x 2 above corner, sk2, repeat from * four times, [(dc2 into 1ch) x 2, sk2] to last 3chs; (dc2 into 1ch) x 2, dc1 + RC1
Repeat the pattern starting from 7th row.

Join the back and two front parts together
Use a larger size crochet hook to widen the fabric.
29th row - h4ch, *[(dc2 into 1ch) x 2, sk2] to corner; (dc2 into 1ch) x 3, skip shoulder part, dc2 into 1ch above next corner, repeat from * two times, [(dc2 into 1ch) x 2, sk2] to last 3chs; (dc2 into 1ch) x 2, dc1 + RC1

31st row – h3ch, dc to last 1ch; dc2 into 1ch + RC1 (you should have 3 initial chs and 123 double crochets or multiples of 4 chs)

Work the pattern without increasing chains
33rd row – h4ch, dc1, dc2 into 1ch, sk2, [(dc2 into 1ch) x 2, sk2] to last 3chs; dc2 into 1ch, dc2 + RC1
35th row – h4ch, dc to end + RC1
Repeat the pattern starting from 33rd row.

Decrease
46th row – h2ch, sc2, sk1, sc to last 3chs; sk1, sc2 + RC2
47th row = 35th row
48th row = 46th row
49th row = 33rd row
Repeat the patter starting from 46th row.

58th row – h2ch, (sc2, sk1) x 2, sc to last 6chs; (sk1, sc2) x 2 + RC1
59th row - h4ch, dc1, (dc1, dc dec1) x 3, dc to last 12 chs; (dc dec1, dc1) x 3, dc dec1*
* work unfinished dc1, sk1, unfinished dc1, and then finish the dc – draw the yarn though all three loops on your hook
60th row = 58th row

Work sc rounds around the body increasing one chain in each bottom corner.

Sleeve
Attach the yarn under your arm and make two chains to pick up the height.
1st row = 33rd row (body)
3rd row = 35th row (body)
Crochet the four row pattern without decreasing chs to about half of your sleeve, and then decrease one repeat/4chs.
At the end of the sleeve work just single crochet rows.

Sew sleeve sides together.