Dear Danna,
Thank you for sharing your story. I'm very sorry to hear you have had a difficult time and I admire your courage to detail your experience here.
You are absolutely right, although healthcare professionals encourage the idea of having a support network, it is possible that a person struggling with their mental health will develop depression because of a lack of one in the first place.
You have also correctly identified that the follow-up should have been sooner than 3 weeks. The ideal time is one to two weeks. Even before then, there should be an easy way to contact a healthcare professional if you feel unwell from taking antidepressant medicines. For example, calling your doctor or calling / walking into a pharmacy for easy access to help. In the UK we also have a general health helpline on the NHS where you dial 111 for free at any time of day and a qualified health professional can help you with your health problem.
I have heard of serotonin syndrome and I completely agree that it is definitely a side effect that should be talked about and taken more seriously too. I'm sorry you experienced that as a side effect.
I hope your situation has improved and I appreciate that it takes time as well as trying different techniques for one's mental health to fully recover so they can have a better quality of life. Even then, the journey we call life has its ups and downs.
I wish you the best.