In the past I named my son, and then later I was told that the name was haram and feminine. So we changed his name legally to Amin, alhamdulillah. Later we found out from a visiting scholar that his name was not prohibited, but alhamdulillah. 

I just had another baby. We took about 7 days choosing a name. I read the story about Barakah and how she was the wet nurse of RasulAllah salalahu alayhi wa salaam. So I named my baby after this sahabiya. We asked the imam about the name, and people in the community, and everyone said it was a nice name. Then the day after the aqiqah sisters sent a message telling me it's haram based on a hadith in Sahih Musim. 

Why didn't rasulAllah make her change it? Is it really prohibited?

In the name of Allah, the Most Merciful, the Grantor of Mercy

All praise belongs to Allah, and may prayers and peace be upon Allah’s final Messenger.

Using those names is disliked, but not prohibited. The reason they are disliked is that one may ask you, ‘Is Baraka (blessing) at home?’ and you say ‘no,’ so the answer sounds bad.

Since the name is not prohibited, the Prophet didn’t change her (Baraka's) name.

The hadith in Muslim about the name Barakah is narrated by Jabir (may Allah be pleased with him), who said,

"أَرَادَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنْ يَنْهَى عَنْ أَنْ يُسَمَّى بِيَعْلَى وَبِبَرَكَةَ وَبِأَفْلَحَ وَبِيَسَارٍ وَبِنَافِعٍ وَبِنَحْوِ ذَلِكَ، ثُمَّ رَأَيْتُهُ سَكَتَ بَعْدُ عَنْهَا فَلَمْ يَقُلْ شَيْئًا، ثُمَّ قُبِضَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَلَمْ يَنْهَ عَنْ ذَلِكَ."

“The Prophet (blessings and peace be upon him) intended to forbid the names Ya’la, Barakah, Aflah, Yasaar, and Nafi’, and their likes, then I saw that he didn’t and then he died without forbidding that.”

In other hadiths, it was reported that he (pbuh) fobade many of those names; so what is meant in this hadith is that he intended to emphatically forbid them (tahreem) but he didn’t, so they remained only makrooh (disliked).

It has been reported also that Ibn 'Umar called his freed slave Nafi’, which is one of those names that are disliked. No condemnation by the Sahabah (Companions) was reported concerning that. Therefore, it appears that the dislike of those names is a “light” one, and for a certain concern they may be avoided to a great extent. I don’t think you need to change your baby's name. 

Allah knows best. 

Related fatawa: 21746, 23268, 79185, 78793