Doubts due to child Marriage

This is something that is causing me to lose faith in Islam. I understand that Islam allows child marriage and learned that it allows consummation with a bride who is prepubescent, even if they are not 9: The fact that it is permissible to marry a young girl does not mean that it is permissible to have intercourse with her; rather that should not be done until she is able for it. For that reason the Prophet (peace and blessings of Allaah be upon him) delayed the consummation of his marriage to ‘Aa’ishah. Al-Nawawi said: With regard to the wedding-party of a young married girl at the time of consummating the marriage, if the husband and the guardian of the girl agree upon something that will not cause harm to the young girl, then that may be done. If they disagree, then Ahmad and Abu ‘Ubayd say that once a girl reaches the age of nine then the marriage may be consummated even without her consent, but that does not apply in the case of who is younger. Maalik, al-Shaafa’i and Abu Haneefah said: the marriage may be consummated when the girl is able for intercourse, which varies from one girl to another, so no age limit can be set. This is the correct view. There is nothing in the hadeeth of ‘Aa’ishah to set an age limit, or to forbid that in the case of a girl who is able for it before the age of nine, or to allow it in the case of a girl who is not able for it and has reached the age of nine. Al-Dawoodi said: ‘Aa’ishah (may Allaah be pleased with her) was reached physical maturity (at the time when her marriage was consummated). Sharh Muslim, 9/206 واختلفوا في وقت الدخول بالصغيرة فقيل لا يدخل بها ما لم تبلغ وقيل يدخل بها إذا بلغت تسع سنين ، كذا في البحر الرائق . وأكثر المشايخ على أنه لا عبرة للسن في هذا الباب وإنما العبرة للطاقة إن كانت ضخمة سمينة تطيق الرجال ولا يخاف عليها المرض من ذلك ؛ كان للزوج أن يدخل بها ، وإن لم تبلغ تسع سنين ، وإن كانت نحيفة مهزولة لا تطيق الجماع ويخاف عليها المرض لا يحل للزوج أن يدخل بها ، وإن كبر سنها وهو الصحيح and this is causing me doubts because medical knowledge shows there is much harms associated with early intercourse and pregnancies. I read that today while child marriage may not be allowed, it is only a temporary change and not ethical one and the ruling still exits. Lastly, history shows past societies had limits, laws and advised against early consummation and pregnancies as they were aware of the harms and risks with it. Thus I wonder why does Allah who is all knowing allow something that's harmful