yarın zorundayım gitmek hastane..
tomorrow i have to go to hostpial.

Yarın hastaneye gitmek zorundayım.

From gramatical point of view absolutely correct,just dont forget to pay attention to the structure of the sentence,the word order etc.

Derya, sen de amma hızlı silah çekiyormuşsun yahu! Yetişemiyoruz bir türlü sana!

-e is the original suffix, but it changes due to the LAST VOWEL, LAST CONSONANT and LAST LETTER of the word which the suffix comes after.

1)

to the house:ev+e= eve
LAST LETTER is a consonant, so we DON'T need a buffer, and THE LAST VOWEL is e in the category "soft vowels" (see the page for more: http://www.turkishclass.com/grammar_vowelHarmony1.htm )
And we add our suffix as -e because of the LAST LETTER and LAST VOWEL: eve

2)
Let's change our LAST VOWEL and take a "hard vowel"... For example o... Let's take the word telefon

to the telephon: telefon+e= telefona
As you see, LAST LETTER is a consonant so we dont need a buffer, and LAST VOWEL is a "hard vowel" so we need to change the suffix as a hard vowel "-a"... Result:
telefona

3)
Let's change our LAST LETTER and take a VOWEL... For example the word: pencere

to the window: pencere+e =pencereye
LAST LETTER is a VOWEL, so we NEED a buffer. It is here y, and the LAST VOWEL is e in the category of "soft vowels", so we need to make our suffix as a soft vowel: -ye Result:
pencereye

4)
Let's change our LAST LETTER and take a hard vowel: masa

to the table: masa+e= masaya
LAST LETTER is a VOWEL, so we NEED a buffer. It is here y, and the LAST VOWEL is a in the category of "hard vowels", so we need to change our suffix as a hard vowel: -ya Result:
masaya

another example for 4):
to Ankara: Ankara'ya

and your word: hastane
Could you see, which one is suitable for you?

Ok, I will say, it is 3)

to the tospital: hastane+e= hastaneye

LAST LETTER is a VOWEL, so we NEED a buffer. It is here y, and the LAST VOWEL is e in the category of "soft vowels", so we need to make our suffix as a soft vowel: -ye Result:
hastaneye

That's it!
I hope it is useful for everyone...