1-according to general common meaning its NOT mean ONLY( Unless used in the exception or to show difference some thing special -which mean the complete meaning include only but not the form (Composition of the sentence ) its more like ON OTHER HAND /BUT because only sould become at first or end to give its meaning but in this case for انما its just at the middle just like :-
ex: الكل يستطيع الاكل انما انا صائمة =every body can eat انما im fasting .
ex:كل عائلتي تحب الحلويات أنما أختي تفضل الطعام المالح = All my family loves sweets, انما (unless/except ) my sister prefers saulty food (here its more close for meaning ما عدا / إلا
2- its used for meaning IN FACT just at first of sentence
ex: انما المؤمنون اخوة = in fact (انما Believers are brothers ..in this case its just used to show deeper and more confirmation but we could understand the maaning with out mention انما
3-it has meaning of RATHER in the middle of sentence
ex: القدس لا تَهُمُّ العرب وحدهم إنّما تهمُّ المسلمين والمسيحيِّين في العالم كلِّه
=Jerusalem does not concern Arabs alone,) but=انما( Muslims and Christians throughout the world.
..finally wish i could exploitation my english to give clear meaning similer like i want to say by Arabic ..all the best