Personally, I feel that the online marriage strategy is not very reliable, and I can't find it many times according to the steps.
There are a few things that I care about. Is yours the original or the enhanced version? There is no wedding story in the original book. In addition, have you ever paid attention to the dependence of the protagonist?
Let's start with Bai Xiaoqing. You said you met in Hebei, so you need to move to any city in Bashu area (if Chengdu doesn't work, try another city), and then wait at least 60 days before you try again.
Only one wife can get married without modification. And you have triggered the first plot of marrying Bai Xiaoqing, which may lead to Qin Xianglian's plot not being triggered. But this problem has never been encountered before. Generally, if Bai Xiaoqing is bored, don't trigger the plot casually. Since it triggered, just accept her. Of course, it may be that your RP is not good enough and you can't meet it n times.
If it really doesn't work, just download a marriage modifier and change it. Although you will have no sense of accomplishment, it is the most convenient way, so don't worry.
If you have any questions, please ask; If my answer solves your problem, please adopt it and give it a good comment ~