Hi @Zeddyborn 
Firstly thank you for bravely sharing your feelings and experiences with us. It sounds like you’ve been through a lot, and I appreciate you sharing your experiences with me. I want to applaud you for being proactive in seeking recovery, trying new things like work, and not giving up even though you were not accepted the first time. 
Leaving your comfort zone takes great strength! Well done on starting school even though it felt scary. Please know there is nothing wrong with you and it’s normal to feel low when the situation around you isn’t what you hoped for.
I’m curious about the inverted commas you put when you mentioned ‘interest’. Does that mean that it isn’t your genuine interest or does it mean something else?
If IT is your genuine interest, then please know that the start of any new academic journey is usually filled with some discomfort. It can take up to a few months to find your footing and momentum slowly. Your uncomfortable feelings are valid. Starting school again after some time away can indeed be overwhelming, especially when faced with challenging subjects like programming and mathematics. These are subjects that are tricky for quite a lot of people (including myself) This does not mean that something is wrong with you if you don’t understand the topic now. This just means that it might take you more time to bridge the gap in your knowledge and skills in these topics. Having a growth mindset will be helpful as you learn at your pace.
May I suggest speaking to your lecturers to see how you can get the support needed to get better in these modules. Perhaps there is a student support group that you can join. I’m glad to hear that you have helpful classmates. Classmates sometimes may have the best intentions to help and they may not be good teachers because they may not have the teaching skillset needed to help you learn better. We all have different learning needs and styles and that too is okay. It is understandable to lose interest in the topics when it feels too difficult. With the right support, the interest can be slowly developed.
Sometimes the first two modules may be unpleasant and the other modules may feel easier after a while. It is also normal to be grieving the loss of your old life at work which was filled with familiarity and comforting colleagues. It makes sense that you would be experiencing low feelings as you need to develop those comforting friendships from scratch again in this new environment.
From your sharing, you sound like someone who has the resilience to continue even though you face hardship. You mentioned that your work environment was filled with multiple difficulties initially and yet you managed to overcome them slowly. Likewise, I believe you will also be able to overcome these challenges slowly. You don’t have to do it alone, you can reach out for support from lecturers, the school counselling department, or other trusted adults in your family or friends circle.
Stay in touch with your current friends that may not be in your poly to feel connected and give yourself time to develop new friendships. Poly is a great place to meet all sorts of different people, allow yourself the time and space to explore your interests via CCA or activities to find friends with similar interests.
Also, given your history of depression and schizophrenia, it’s important to pay attention to how you’re feeling. If you’re experiencing a lack of enjoyment in activities you used to like and struggling to focus, it might be helpful to reach out to your psychiatrist and mental health professional for support and guidance.
Remember, it’s okay to take things one step at a time and to prioritize your well-being. You’ve shown resilience in facing challenges before, and with the right support, you can navigate through this difficult period as well. You may want to practice self-compassion to help you navigate this new chapter in your life with a little more ease. I’ll share some resources below for your consideration.
I hope the above helps and wishing you the very best! 
Here are some additional resources for you to consider:
Rescue Session: Rescue Sessions | mindline.sg
Learning Paths: Learning Paths | mindline.sg
Feel More Control: https://mindline.sg/youth/?wysa_tool_id=feel_more_control
Be Kind To Yourself: Mental Support & Wellbeing Resources in Singapore to Improve Your Mental Health | mindline.sg
Boost Your Mood: Mental Support & Wellbeing Resources in Singapore to Improve Your Mental Health | mindline.sg
Managing Feelings & Emotions: https://www.youtube.com/watch?v=Vs-MyQgfH3A
Belle from Beyond the Label: Messenger
CHAT: Get Help - CHAT
Kind regards,
Cool Breeze