As another person pointed out as well, the problem here is really the white belt. If it was two purples it would be fine. I am over 230 pounds and had a great set of rolls with a 140 white/blue belt woman.
We were technical, I made sure to make her work, and didn't go out of my way to overpower her. Sure I'd submit her, but I would really try and limit myself to pure technique. Even then it's a struggle because even when I don't feel like I'm using much strength, it can be more than she might reasonably be expected to stop. At the same time I let her progress and she armbarred me several times; why? Because I'm not so prideful that I wouldn't let her get somewhere if she was being technical and trying.
When she wanted my back from side and was doing the right things to get it, why would I just use my weight to prevent her? I struggled a bit, then let her move me where she wanted. When she went to take my back she quickly switched to a sakuraba armbar. Sure I saw it coming and could probably have pulled my arm out and defs could have stacked her and prevented the submission...but why? It was a good transition and I tapped once she got it extended. We reset and moved on like the non-issue that it was.
White belt dudes are so caught up in not tapping to the girl that they freakshow on women as hard as they can, in ways that they'd never try with me. I can't tell you how many girls I've seen catch knees or elbows in the middle of a smash pass from some douchey guy who is convinced he's going to get his first win of the day over this girl.
The other interesting part of this to me is that the overwhelming majority of people giving OP a hard time or ranting about women or whatever - it's all the white/blue belts. Most purples + have been around long enough to get it, they've trained with women, they've seen the spazzy white belts, the ego-driven gym rats that come through now and then, etc... and it's the purples + that seem to be the moderating voice in the discussion. I think that probably says something.