I have short/flat nipples. Lo latches on though. But I'm worried that once bottle introduced he will prefer the bottle due to longer teat aka "nipple" and reject my nipple and forego latching altogether. I'm really afraid and don't dare to introduce bottle to be honest..I failed latching my #1 in the past and don't wish to fail with my #2 now that things are going ok the past 1 month...sigh..

You may want to consider going for a teat similar to your nipples. Having said that babies are smart to differentiate between mummy's nipples and bottle teat. Also avoid upsizing the bottle teat until they are older. Fast flowing teat will allow effortless drinking. One of the brands you may consider will be Pigeon peristaltic ss teat. Some recommends NUK teat. You may also want to consider alternating latching and bottling in the daytime and purely latching at night.