Message not any later than usual! I am fine, just missing you as always. You are for ever  in my thoughts no matter what time of day or night.

(modified) Iyiyim, sadece her zaman gibi, seni özlıyorum.  Gün ve gece tüm saatta, her zaman aklımdasın

My attempt

I have (hopefully!) translated as ´I am fine, just missing you like always.  Every hour of the day and night you are always on my mind´ - because not sure how to translate ´for ever in my thoughts´

Aargh!!! - you added something!!

Message not any later than usual!  - not sure of that one - sorry!

You are always on my mind could be ´daima/her zaman aklımdasın´

sorry LIR-I didn´t see your bit!

 No - you´re right I´m amending mine!  Just got lost on the ´you are´ bit!

It´s fine as it is - forget the added bit. Didn´t think anyone would be up so early when I added that bit on. Thank you so much for your help