I bought chrysanthemum in the end.

I bought 1 stalk of red chrysanthemum with 6 flowers bud + 1 stalk of white chrysanthemum with 6 flowers bud.
I read from an online article that if I wish for a boy, I have to bring odd number of white flowers (e.g. 11) and if I wish a girl, I have to bring even number of red flowers (e.g. 12). But if no preference, bring 6 of each.
I didn't know to buy 6 stalks or 6 flowers. I chose 6 flowers in the end because 6 stalks of each colour will be too huge. I was afraid there won't be sufficient space on the altar for such a big bouquet. So I bought 6 flowers of each colour in the end.
I visited TPY temple on Saturday afternoon. I called in advance to ask whether there were red eggs. The lady said yes. But when I went down, I couldn't see any on the altar. So I asked and was told that the lady gave me wrong info.

Nevertheless, my hubby and I prayed sincerely and took 1 sweet each from the altar as blessings from ZSNN.
Today, my office has a colleague who sent full month celebration goodies for us to enjoy. I took the chance to bring home 2 red eggs, 1 for me, 1 for hubby. Hopefully baby dust through this method works!
-keeping my fingers crossed-