How to increase milk supply?

Hello everyone! So my son is almost six weeks old, and I’ve been pumping and formula feeding him. I’ve been trying to produce more breast milk for him, but it seems like no matter what I do, it’s not working, and I’ve tried almost everything. I used to produce at most 1oz once a day, but now it’s way less. I don’t want to give up, but I don’t know what else to do to get my milk supply to come in and produce more milk. I was wondering if my SO we’re to suck the milk out if it would help bring in more milk?? I know it’s weird, but my son won’t nurse from me. The most he’ll do is have the nipple in his mouth for a few seconds and spit it out. I really don’t want to give up on trying to bring in my milk for him since he was born a late premie. But IDK what else to do. The only thing I haven’t tried is the mother’s milk tea, which I am going to buy and try out, but I was wondering if the whole idea with the SO would help?