At six weeks old she's hitting a growth spurt, but eating every two hours is normal. If you try feeding her more than the 3 oz you typically give her just because she's screaming and she spits it up that's because you've either a.) overfed her and tummy is expelling the extra food or b.) her tummy is too full of air and roiled up from the crying and screaming to hold anything additional down.
When she goes two hours in between, are you waiting for her to get to crying before you feed her? Or are you watching her body language and listening to her vocalizations for signs of hunger before she gets to upset crying? If you know she's going to be getting hungry then be sure you have everything as prepared as possible prior to the feeding.
Less upset scream crying means less air in her belly and less air in her belly means less spitting up.
Start keeping a journal for her. In the journal keep track of when she starts her meals, when she pees, poops, and starts/ends her naps. Keeps track of how much she's eating. You'll be able to notice patterns more easily if you're writing them down and you won't have to rely on your memory for details. If you see something that you need to remember, like bloody stool or she ate an extra ounce and held it down, or she slept an extra half hour in between feeds and might need an extra half ounce, you'll have it in your journal. This will also help your spouse so that he can easily take over if you need a nap or a shower and he can just look at the journal to see what to do.
If she spits up frequently, like more than in some mucus or a burp, and it ends up looking like a third or half of her meal, if it comes up curdled, note that. It could be reflux.
If she seems to burp but "swallows" it, note that. Especially if she cries after. That's a sign of reflux.
If her body stiffens when she burps, before or after, that's a sign of reflux.
Personally, your post is showing some signs that she has GERD/reflux so I think you need to get her to a pediatric gastroenterologist. You don't need your pediatrician's permission to do this, although you might need a referral depending on your insurance. There are some simple tests the GI specialist can do and they can help your baby not be in pain when eating or after, and make feedings easier for both of you. They can also set you up with a pediatric nutritionist in the event that your daughter needs a different type of formula.