Hi again Shish.
I know where you are because I was there too, I can remember how desperate I felt.
DS refused a bottle completely so I gave up bothering. He fed little and often, and threw up after every feed, so there was no way I could force more down him.
At 19 weeks I was still feeding him at least 6 times in the day (once every 2 hours on average if my maths is right) AND he was having lunch & tea too, AND he would feed at least once at night and in fact often woke mid-evening for a quick feed as well.
My days were quite routine-ish because he woke up the same time each day and I did the same things roughly at the same time each day.
E.g. I always went out at around 9.30 each morning. I rotated it, supermarket, town shopping, NCT coffee morning, walk to the paper shop, whatever, we did it.
I wuold top DS up with milk before we went out, he would nap in the pram or car, and then would feed again when we got to our destination.
Then I worked out the rest of the day in a similar way. Often I fed him when I thought he needed it (based on the rough pattern that was developing) rather than wait for him to start crying.
I think that's how I did it.
Anyway I was still BF at 19 months (one nice bedtime feed, that's all) - hard to believe when I nearly gave up loads of times in the early days because I felt like you do.
I threw all my books (including the one we musn;t mention) out of the bedroom window in a fit one day when DS was tiny and I couldn;t seem to establish any kind of routine and felt I was going completely insane.
Keep going with the BF. Try to coax things into a pattern. It will work, honest.