We have two dds. Our oldest is HG and clearly so like your boys. Our youngest is also HG, apparently, but save for very early talking (putting two words together at 5.5 months), there was nothing major that made me think 'gifted' with her either. She did read a bit early and reads fairly well, but she doesn't like to read. She is much more interested in social and non-academic stuff than things that would make her appear to be gifted.
She's also 2e. 2e kids may not appear nearly as gifted as they are. Girls also may not appear as gifted as they are. Girls with very high performing older sibling may be in a shadow in that regard. With all of the possibilities and two HG siblings, I'd also test your dd if you can afford to do so.
I really think that my dd11 is doing better being recognized for being HG to some extent even though it has been a long road and she's doubted herself a lot too. When I think about the alternative -- having her tracked into non-accelerated classes across the board, assumed to be high-average, etc., I really don't think that she'd be as happy as she seems this year. She isn't high average even if there are challenges that make her appear that way at times.