I really want to keep nursing my baby

My baby is 6 month now. Since she was born, I did not know how to breastfeed my baby effectively so she slept on my boobs most of the time without taking any milk. And we introduced her formula since day 1 while I tried to pump. At that time I only pumped 20ml, 40ml both sides so I freaked out and thought I was a low supply.

I triple fed my baby since then, and continued to pump every 3 hour except the night. When I pumped 40ml, she drank a bottle of 60ml, when I pumped 60ml, she drank a bottle of 90ml, when I pumped 90ml, she drank a bottle of 120ml. I kept chasing her like that.

When she was 3 month, she refused to take bottles and insisting on nursing. At first, I was worried a lot that she was never get full. But she kept refusing bottles so I only nursed her. At first she nursed a lot and gradually it got better. She had 6-7 wet diapers a day and she can sleep whole night with only 2 wake up at night to eat. I was very very happy because I thought finally I could exclusively breastfeed her.

But when she was 5 month and until now 6 month, she is not satisfied at breasts, she keeps grazing at my breast and making uh uh sound while waiting for the letdown, and i can feel the letdown is very slow. After the 1st letdown, she will stop latching, sometimes she tries to keep latching to wait but seems like it takes forever. Only when she is sleepy then she will be very patient, i nurse her to sleep but she will wake up if i unlatch her, or she can only sleep 30 minutes. So I think she is hungry and sleepy at the same time. She has around 5-6 diapers and she is still active between feeds, just only that she keeps nursing so often (before nap, after wake and 3-4 times at night)

I made her a bottle of 170ml today and she drank 150 ml and she slept for almost 2 hour straight, she only need my boob for several minutes at first to settle down, not keep latching for the whole nap like when she only breastfeeding.

I pumped when I offered her the bottle but only got 70ml…

Seems like she was never feel full during the time of breastfeeding. I have a mixed feeling, part of me feel happy when she can have a full meal and good sleep, but the other part of me was very miserable. I have always been obsessed about milk supply, i want to nurse her until when she wean off, because i know she loves nursing even until now. She refuses the bottle at first and wants to nurse but she is frustrated at the breast then she agrees to take the bottle.

What should I do, I am afraid that I starve my baby if I keep only breastfeed her, but also if I pump while offer her bottle of formula. I need to pump every 2-3 hour in order to increase the supply.