Must I pray with an ablution that might be nullified by secretions, or should I wait until I return home to pray both prayers together?

If a woman confirms the discharge of secretions, her ablution (wudu') is invalidated. If the prayer time arrives and she searches for a place to perform ablution but finds none, and the prayer is one that can be combined with another (like Dhuhr with Asr, or Maghrib with Isha), it is permissible for her to delay the prayer and combine it with a delayed combination using water ablution, provided that her return home is before the time of the second prayer expires. Shaykh al-Islam Ibn Taymiyyah said that combining two prayers with water purity for one who has an excuse (such as rain, strong wind, urinary incontinence, or irregular vaginal bleeding - istihada) is better than separating them with an incomplete purity. However, if the prayer cannot be combined with the one after it, then she is obligated to pray with tayammum (definition) (dry ablution) in any pure place suitable for prayer. It is not permissible to delay the prayer until its time expires, because the Sharia (definition)'s consideration for the time is greater than its consideration for all conditions and pillars that one is unable to fulfill.