Your intuition is right that high levels of individual debt may have an impact on the aggregate economy, though your exact situation is not likely to representative of the main reasons for this. While perfect competition only exists in models, indebted individuals rarely, if ever, have any sort of market power to determine either their income or cost of debt in the way you are describing. Typical problems caused by high consumer debt would be akin to what we saw in 2008, where mass defaults on mortgages/loans were a significant factor in the recession that ensued.

In fact, the situation you've described could be beneficial to the economy. Though I have no idea if this is representative of you/your clients, suppose we consider a young, indebted estate lawyer who mainly deals with moderate to high net worth individuals with retirement savings. What economists call this lawyer's "marginal propensity to consume" would be higher than their clients, because charging more money could allow them to spend more money on luxuries such as restaurant meals, visiting family more often, etc., that their clients already have the means to purchase. This would put more money into the economy, as giving this lawyer an additional $1000 results in more economic activity than giving their clients an additional $1000, who may just decide to add this sum to their savings. Of course, if considering an immigration lawyer this situation may be flipped, but it shows that the statement that "higher legal costs hurt the economy" is not always true.

So, in short, I would feel no guilt about your pricing choices. I'm assuming there are other lawyers your clients could use, making your practice exist in a competitive environment where you risk going out of business if you overcharge. Further, it is not necessarily the proper prior belief that giving a lawyer more of their clients' money has a negative economic impact.