tax concern as a freelancer

Hi, I'm a freelancer since 2020. I earned below the annual tax income until this year. Now I earned about 300k+ this year and hopefully higher next year. As I get older, I'm starting to want to pay taxes due to wanting to pay SSS and all that kind of adult stuff documents. I'm dumb af, I have no education, and I dont know anyone... people tell me "it's okay you're a freelancer, you dont need to tell anyone about your income." they dont know i want to pay taxes, SSS and get TIN. Please don't judge me, I'm already feeling like a tax evader and a horrible person... I get that a lot and then I just shut down and don't tell anyone again.

Now, what I'm afraid of is what are the consequences if I go to BIR, will they check my accounts for proof of income? Will they ask why I have 2020-2023 income (that are all below the tax annual income). Will they check my bank info, Gcash transactions, etc?

Now my income is UNSTABLE. For example I open work for September, earn 70k or more, and then don't open for work until all that money is gone towards my family and I's expenses. There are times I have 0 income. How is it all calculated by end of the year? I have no idea at all... My income is very unstable, it's up and it's low, i have earnings this month then nothing for 3-4 months. Please enlighten me how is income tax paid? Every end of the year? Every month? Do I need to hire someone and if I do what info do I give them? Do I give them all my transactions? What if my work transactions is a headache, it has my electric bills, my purchase of a donut and weird stuff, my purchase of a candy bar or a pack of antibiotics, what if 4 months of that is just purchases of family expenses do I give those to them?

Sorry, just frustrated, I don't know anything about taxes...