I didn't read all the reply, so sorry if this is repeated. Be sure to follow the directions on the package to a tee. I used Nestle's Good Start w/ DHA & ARA. I had some issues in the beginning w/ it not mixing well also. So, I called the CS number on the package and asked them to walk me through it. One thing I was doing incorrectly, per another person's incorrect instruction, was to pack the scoop sometimes. See, the scoop was curved at the bottom, and had a hole in it. The instructions were to put a level scoop in the water. I was sometimes putting in a packed level scoop. The curved bottom is intended to have an air pocket when filled. Don't ask me why. However, it made a huge difference. It mixed easier, and my babies tummy was happier as well. I spoke w/ many moms using the same brand, and they did the same thing. Afterward, they too stopped having constipated babies and issues with mixing formulas. With to much powder, it's rich/high in calories, not to mention harder to digest. So if there is any question, don't hesitate to call and ask questions. I also started used a small battery operated drink mixer to mix - and that helped save what little energy I had preparing formula. I think I did 1/2 the amount of water slightly warmed filtered water, added formula - mixed until dissolved then added room temp water. I'd mix at least 12 hrs worth at a time and labeled them - rotating freshest to the back and oldest to the front of a row of container I made. At feedings I'd warm some water, pour a bottle and put in warmed water until just right.
In addition, it's totally worth registering w/ the companies that make the formula(s) you use. Nestle sent me not only a full can of Formula EVERY month (just about), plus they sent several coupons to help buy more. I also used WIC. Many times those coupons really helped. And don't be afraid to try less expensive store brands. They are usually manufactured by one of the name brands with a store brand label, and are much less expensive.