All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is nothing wrong for a woman to ask that the one who proposes to marry her suits her and fulfils her. However, if she does not find such a husband, then she should not refrain from marriage if she does not find someone who meets the qualities that she wants, because she might miss out on a lot by doing so, and men could stop proposing to her as a result.
Religiousness and good moral conduct are the most important qualities to be considered by a woman when deciding on the man who proposes to marry her.
Abu Hurayrah narrated that the Prophet said: “If a man whose religiousness and moral conduct are pleasing to you proposes to you, then marry your daughter off to him; otherwise there will be great mischief and corruption on earth." [At-Tirmithi]
The Prophetic instruction here only recommends this and does not oblige it as stated by the scholars. Therefore, you are not sinful if you refuse this man’s proposal. However, if he is religious and has a good moral conduct, then we do not advise you to reject him. Rather, repel those evil thoughts and fears and accept him as a husband perhaps Allah will bring much goodness for you.
Do not forget to perform the Istikhaarah prayer about him before accepting him so that Allah will choose for you that which is better for you. For more benefit on the Istikhaarah prayer, please refer to Fatwa 81434.
With regard to delaying childbearing, if there is a legitimate benefit for that, then you can have a mutual understanding with him after marriage. If you both agree to delay having children for a temporary period, then this is permissible in the Sharee'ah. In case he refuses, then perhaps Allah will bless you from him with righteous progeny that will be a comfort to your eyes in this worldly life and the Hereafter.
In addition to this, it should not be forgotten that one may delay having children while they are able to have children, then some obstacles may happen or some calamities would strike them and prevent childbearing. In fact, we have seen that some examples when women were forced to have tubal occlusion for whatever reason (health reasons) or the husband becomes paralyzed and cannot have sexual intercourse with the wife.
Allah knows best.