If you add any positional ending (accusative, dative, locative, ablative, genitive) after the possessive ending of the singular and plural third, you have to put a helper "n" between them.

ex:

bilgisayar            + ı (possessive)
>bilgisayarı
his/her computer

bilgisayar            + ı (possessive)    + a (dative)
>bilgisayarına
to his/her computer

koca                    + ı (possessive)
>kocası
her husband

koca                    + ı (possessive)    + dan (ablative)
>kocasından
from her husband

This is the same for the possessive determiners as well:

ihtiyaç                : necessity

ihtiyacım            : my necessity

ihtiyacım var    : I have necessity            > I need

yazma pratik + i (possessive)
>yazma pratiği
writing practice

yazma pratik + i (possessive) + e (dative)
>yazma pratiğine
to the writing practice

Yazma pratiğine ihtiyacım var.
I need writing practice.
(literally: I have necessity to the writing practice)

Bu yüzden şimdi yazma pratiği lazım.
(That's why the writing practice is necessary now.)

Bu yüzden şimdi yazma pratiğine ihtiyacım var.
(That's why I need writing practice now.)

"ama hiç yok yazarak" makes sense, yes. no need to correct it. but may you rewrite it in English? perhaps I see that any other detail.

The indefinite possessive determiner:

OWNER NOUN            BELONGED NOUN + posessive

. . .

yazma pratik + i 
>yazma pratiği
writing practice

Yazma pratiği lazım.
Writing practice is needed/neecessary.

Bana yazma pratiği lazım
I need writing practice.
(literally: The writing practice is necessary to me)

for fun:

bana yazma pratik + i
>bana yazma pratiği
practice of writing to me

LOL

-m is the possessive ending

1) If the word ends in a vowel, it is barely added

seviye              : level
seviyem          : my level

araba               : car
arabam           : my car

2) If the word ends in a consonant, it takes the ı/i/u/ü helper sounds according to the vowel harmonies rules.

öğretmen        : teacher
öğretmenim    : my teacher

arkadaş           : friend
arkadaşım       : my friend

_________________

-im   is the personal ending.

1) If the word ends in a consonant, it is added as -ım/-im/-um/-üm according to the vowel harmonies. It has the same appearance as the possessive ending in this situation.

öğretmen        : teacher
öğretmenim    : I am a teacher

kadın                : woman
kadınım            : I'm woman

2) If the word ends in a vowel, it takes the "y" helper consonant.

yabancı               : foreigner, stranger
yabancıyım        : I am foreigner, stranger

öğrenci             : student
öğrenciyim       : I'm a student

-dır/-dir/-dur/-dür
1) (for verbs) causative voice                                      there are one suffix more
2) (for adverbs) for                                                        since past
3) (for predicate) official speech                               
4) (for predicate) guess, possibility, uncertainty      
5) (for predicate) generalisation
6) (for predicate) examplifying

. . .

çok zaman                    : much time
çok zamandır               : for much time, for a long time

bir yıl                              : one year, a year
bir yıldır                         : for a year

üç gün                           : three days
üç gündür                     : for three days

Çok zamandır seviyem aynı.
(My level has been the same for a long time.)