Thanks Lisa, but I'm a little confused by some of the information. I've always been told to ride with flat back, pelvis rotated forward, imagining trying to touch the top tube with belly button, etc. So I have always tried to ride with a flat back and achieving that by rotating my pelvis forward. When I said forward/down I was referring to rolling my pelvis forward and down getting in the drops. I checked with my husband who I ride with primarily and a friend and both say although my back isn't perfectly flat (slightly rounded in the upper part) the lower part of my back is flat, not swaybacked.

The other thing is this is an issue with the Brooks and Jamis not my Scott and Zerox.

With that said, I know I could engage my core more (always ) and as you suggest try to pull up at the pubic area. I think part of the issue is the saddle is a little high which would exacerbates the pubic pressure issue as I have to reach at the bottom of my stroke (my husband noticed this when we were out riding the other day).

It helps to be more aware of your whole body floating over the bike, and try to distribute your weight evenly between sitbones, feet, and hands. think of your whole body as floating/walking/swimming over your bike, not just your body sitting on a chair while pedaling.
This describes how I feel when I ride my Scott CR1 Pro perfectly (Terry zerox saddle), feeling a part of the bike, not like I'm sitting on and riding the bike. I don't feel that way on my Jamis which is partly because of the different geometry but I believe, is also a fit issue. Getting the Brooks has changed my fit and the changes need to be addressed. Sigh. I had the perfect fit on the bike prior to changing out the saddle. I felt comfortable while in the drops or hoods with the stock saddle, but my sit bones weren't happy. Funny, but I have the opposite problem with Brooks, sitbones happy, rest isn't/stock saddle everything happy but the sitbones. There is no perfect saddle.

I appreciate your feedback and know it's important to not collapse on the bike but to support myself with my core too, and will keep your pointers in mind when I ride next.

Susan