I have also experienced chronic depression from childhood. I have been able to alleviate my depression significantly through meditation and specific therapeutic modalities. The meditation techniques in Your Breathing Body are truly effective for eliminating the mental and physical underpinnings of chronic depression. The practices on this page are a good starting point.
If you practice body awareness meditation techniques such as those linked above, the bodymind will gradually eliminate the underlying causal factors that produce depression. This process includes deep self-modification of the brain, leading eventually to the deep rapture and bliss of jhana.
The human organism has the innate potential and capacity to liberate itself from negative mental tendencies to the extent that it is possible to entirely eliminate mental suffering. Western psychology has yet to catch up with Buddhism’s deep understanding of how to transform the mind to produce happiness.
I strongly recommend that you try one of the therapeutic modalities that work with emotion and tension stuck in the body, like EMDR, Hakomi, or Somatic Experiencing. I personally found EMDR effective. I once assumed my depression was a chemical imbalance and there was nothing I could do about it, but body awareness meditation and EMDR showed me that I was actually suffering from repressed emotional trauma that I was subsequently able to excavate and heal. I did not find talk therapy effective, but this varies from person to person.
Depression and anhedonia are ultimately caused by lack of mental concentration and attachment. The attachments that cause depression can be deep negative attitudes and imbalances in the subtle energetic systems of the body, both of which are often unconscious. This isn’t something to be guilty about--attachment is the typical human state, and depression is common in the modern world--but it isn’t yet time for you to abandon the path.
The 10 points practice is a great resource from the same teacher. I recommend these techniques for all Buddhist practitioners whose meditation lacks a body awareness component, but they will be especially helpful for those with depression and other emotional issues. The Mind Illuminated is an excellent guide for developing concentration whose techniques can be practiced alongside the ones that I linked above.
To supplement your meditation practice, I strongly recommend that you try one of the therapeutic modalities that work with emotion and tension stuck in the body, like EMDR, Hakomi, or Somatic Experiencing. I personally found EMDR effective along with meditation to alleviate my chronic depression and anxiety. A therapist can guide you in ways that you wouldn't be able to figure out yourself.
If you have time, you can start meditating about 30 minutes daily and gradually work up to an hour. From there you should start working with a teacher (/r/streamentry should be able to recommend some) and move up to 2-4 hours. Take a break from practice and seek guidance if you experience overwhelming emotions or unusual phenomena.
To avoid entering the dark night stages, do not practice insight meditation (such as Mahasi noting) at all. If you suffer from depression, it’s a bad idea to practice insight meditation without first developing the deep concentration, relaxation, and bliss of jhana. Stick with concentration techniques for now.
Minimally, you can incorporate the 10 points practice in hourlong sessions alongside or replacing your daily TMI practice. Following the Sedaka Sutta, it is optimal to maintain mindfulness of body sensations (which can include the breath) at all times when you aren't either engaged in focused activity or observing the other three bases of mindfulness: feelings, mental events, and dharmic classificatory schemes (e.g. contemplating and classifying skillful vs. unskillful behavior).
Thanissaro's treatises, like With Each & Every Breath, explain how to use the breath to develop a holistic awareness of the body. His approach could also be useful.
Your Breathing Body is probably the gold standard of Buddhist meditation instructions for developing comprehensive mindfulness of the body.
Modifying the TMI techniques likely isn't desirable without guidance from a teacher. TMI is certainly compatible with these introductory materials from other systems, however.