Put what you can afford to invest. You done your best so far, because many DCA strategies that most people do stop in the middle of the road because of unstable monthly income.
Don't invest more than what you can afford to lose it all. It is meaningful applicable for all investment strategies, not only for Dollar Cost Averaging.
Because the DCA concept will not only focus on bear markets, each month must have a budget to allocate.
It's not a must. You should maintain your DCA investment regularly but you don't have to do it exactly on weekly, monthly or quarterly basis as you plan initially. You should prioritize more important things in your life. When you have spare money, you can DCA. If you manage to do it regularly, it is good. Else, it does not mean you can not do DCA.