As an individual with ADHD, how should I go about trying to control my impulses?

As you know, the nature of ADHD is that it is difficult to control impulsive behavior. Inattention symptoms can lead to responsibilities being neglected, poor organization and difficulty completing tasks. Whilst hyperactivity symptoms will manifest as thrill seeking, a high need for stimulation and impulsive decision-making.

You say it pervades every aspect of your life, and mention two scenarios of spending money and over-eating in particular, although I understand these are just illustrating two examples of where it can affect your life.

Spending large sums of money could be seen as thrill seeking - buying new "stuff" can initially give a high, but when it is impulsive, it may not exactly turn out to be money well spent, which in turn will lead to regret, and in the worst case scenario, possible financial insecurity. It also shows the symptom of lack of responsibility - perhaps the money would have been better served elsewhere. 

Overeating can often be utilized to soothe overwhelming feelings that come with ADHD, or to try to relieve boredom or stress.

It sounds like it is having a really big impact on your day-to-day life, especially as you say you feel as though you have no control over it. 

ADHD creates structural differences in the brain, most notably in an area that is responsible for impulse control. So, although we cannot alter the structural differences in the brain, there are things we can do to help. You don't mention whether you take medication, but working with a doctor can be helpful for the management of symptoms. Therapy can also be helpful for ADHD.

In therapy we can look both at the past and at the future. Looking back through your life at how it has impacted on different areas of your life - schooling, friendships, your relationship with parents/family, romantic relationships, work life can be important. ADHD can have a significant impact on behavior and therefore on these areas of life, and perhaps you have blamed yourself for this, which is a heavy burden to carry. Understanding those experiences better in a non-judgemental environment in therapy can help you to let go of unhelpful feelings of shame or self-criticism, feeling defeated and low self-esteem that might have arisen from these situations.

We can also look forwards to shape your life better suited to you. Sometimes, there may be a feeling of expectation, perhaps as other people are "wired" differently to you as they are neurotypical, so they are able to do things a certain way. Accepting that their way may not work for you and being comfortable with this, allows for you to develop strategies that work for you in life. Doing things differently can be the answer. Typically, you might try to do things in the way others do, because you have accepted that this is the "right" way of doing things. When in fact, it doesn't work for you and makes life more frustrating and difficult for you. 

In counseling, through psychoeducation, you can also gain an understanding of how you operate, and how your brain and your nervous system operate so that you can manage your life better and overcome the difficulties you have faced. Through understanding comes greater self-awareness and the ability to accept certain differences and also the ability to try different strategies to better manage your life.