The female flowers should follow shortly. Male flowers are borne on a long spindly stem. Behind the female flower there is a tiny bitter melon, less than 1" long.

I have read posts on GW were people waited weeks for female flowers. I think it was the Asian veggie forum.

Something munched off the tips of mine when it was small. I think this may have caused the plant to put out side shoots, where the female flowers are formed, sooner.

Look for female amd male flowers as shown in pic.

Pic. of female and male flower of bittermelon.

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I could not capture the female flower with fruit.Look for the flower with fruit.This one is a female flower.One without a fruit is male flower.
I am posting male and female flowers of Zuccini just for illustration to distinguish male and female flowers.

Pic. of Zucchini flowers.

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Another problem may be absence of pollinators.In this case you may hand pollinate.Pick the male flower (one without small fruit) and transfer the pollon to the near by female flower rubbing flowers face to face.

I agree with the comments above. One other factor could be over-fertilization. With too much N, the vines will have lush growth, but few flowers. Bitter melon does best if you fertilize lightly, use slow-release organic fertilizers, or withhold fertilizer until several fruit have set.

The vines also require full sun to produce a good yield.

Along with full sun as zeedman has mentioned in above posting BM plants love moisture.I spread hay around the plants to retain moisture.

Thanks for your replies guys. Chaman, thanks for photos and explanation. I did notice at least 5 small bm fruits when observed closely.
thanks
a

Hi,
Finally, I got about 5 BMs. Now, the new small BMs are turning yellow. What could be the reason? Too much fertilizer, lack of space(because they are growing in pots)??

Thanks
a

may be the small BMs are not ripe .they r unpollinated flowers

If I see the small BM behind the female flower, does this mean the flower has finished pollination successfully? Or do I need to help the pollination manually?

In my opinion, it's immature/unpollinated but has the potential to become a full-fledged fruit. I think I just saw some article about this. I've found that it's this way in zucchini, watermelon and many others.