The only explanation I can think of for your daughter's behaviour would be that she's hormonal and irrationally angry about everything (get used to it I'm afraid).
Oh, and perhaps she's one of those types who are afraid to feel confident her baby will definitely arrive safely. Perhaps she hasn't dared to buy any clothes herself yet and felt a bit freaked out when she saw how many you'd made.
Have you considered that she may have felt overwhelmed by your enthusiasm? In my opinion, a baby couldn't possibly need more than two or three woollen items, especially if she's already four months pregnant. There are very different guidelines regarding baby's temperature now than previously. I was told to ignore the colour my DD's hands (which were purple) and feel her chest as a guide. This meant she needed far, far fewer layers than older people (like my mum) supposed. It's a touchy subject because new mums are encouraged to see overheating as almost the worst thing that could happen, for fear of cot death. Your daughter could have had all this going on in her head, who knows? It sounds like you've prepared more than you need to - while that's kind, it's important to remember you'll need to take your cue from your daughter. She'll back off if she feels she has to rein you in. Are you usually quite full-on?
Thinking back, I was terrified my DM would take over when I was pregnant, because she always does, about everything. It's impossible to stop her doing it because (a) she's doing it out of love and (b) she'd be so hurt if anyone told her to stop. (And friends have encouraged her to feel martyred if I've ever rebelled, even a teeny bit). That's all fine up to a point - typical mother daughter stuff. But it's also led to many situations where I've had to let DM ride roughshod over my plans, feeling resentfully grateful as she does exactly what she feels like doing. When I was pregnant, I was adamant that this was the one thing that I'd do my way, because that's instinctive as a mum. I have no idea what you are usually like, but if there's any of this going on in your DD's head, you're going to have to accept that your emotions have number four priority - the baby comes first, followed by the parents. It's their time, both to prepare for and step up to. That shouldn't create a conflict of interests provided you're all sensitive to each other - perhaps that falls to the grandparents a bit more. After all, they're dealing with a whole new dimension of responsibility in their lives while you can give this little one back at the end of a day.
And it may be that your DD's a spoilt little madam, in which case you are probably accustomed to this kind of behaviour from her. I sympathise. Why not become a Home Start volunteer and help out a mum who really needs it and would probably grab your knitted beauties with both hands?