Thank you for reaching out; you are definitely not alone. It can be incredibly difficult to lose a parent, especially one who played such a positive and supportive role. It sounds like your mother was a loving and wonderful woman.
From your description it seems like you may have been so busy caring for your brothers that you may not have had a chance to process your own grief following your mother’s passing. Self-care often gets sacrificed when we are grieving or focussed on helping others. It is important to make sure we have daily routines that will support us through this time. It may sound simplistic, but it can be incredibly helpful to ensure that you have healthy, structured approaches to basic things like eating and sleeping. We have some information on our website available here: https://griefline.org.au/resources/east-toolkit/ I recommend taking a look as a first step.
Also, when we experience grief, we can often be reluctant to talk to other people about it. But doing so can be incredibly beneficial, especially if they have experienced something similar. But even if they haven’t, just having someone to listen to us can be therapeutic. Is there anyone among your family, friends, or workmates that you would feel comfortable to talk to? Perhaps reaching out to community or social groups might also be good. There are more suggestions for ways to get help from others if you go here: https://griefline.org.au/resources/understanding-the-symptoms-of-grief/ as well as some ideas for how to continue your bond with your mother even though she is no longer here.
I really hope some of these ideas can be useful for you. Please remember that you are not alone, and that there is no timeline for grief, and no ‘right’ way to do it. But by practicing self-care, reaching out to others, and taking time to yourself when you need it, you can find a way through.