I think love is a collection of emotions rather than a specific emotion in its own right.
I did not love my DC when they were born. I did not have PND or anything, it was just that love wasn't there. I felt an instant sense of protectiveness towards them, but that was about it. Love grew over time, because until I got to know each child better, I simply wasn't relating to them on enough emotional levels to make it meaningful. Over time, as our relationship grew, so did love.
For me, the simplest way I'd describe love is that it it is characterised by the ferocity of whatever emotions are involved in that relationship.
So, for example, like you I feel fear that my DC may be harmed in some way. This translates as a fierce need to protect them - something which only becomes recognisable when their security/well-being is threatened (so quite rare). I also feel joy when they do something really sweet or something that makes me proud, and intense frustration when they do something irritating but ultimately pretty ordinary for children.
Another example with my DP, is that the emotions I feel when he makes me laugh, how much I like his view on life, etc are all emotions I feel with other people, not just him, but he combines more of them in one go and the strength of those feelings is more pronounced. And, of course, I fancy him, which is what separates a friendship from a romantic relationship.
How you 'feel' that ferocity varies from person to person I think. I get a feeling that I want to burst with the intensity of emotion I am feeling. Other people might experience it in completely different ways.
Personally, I think that if you have to ask what love is in terms of a romantic relationship, you probably aren't and have never been in love. It's not about fireworks and starry eyes - indeed it can be much more pragmatic in nature - but there should be no denying the strength of caring.
You say your childhood was complicated. Do you think you amy be suppressing positive emotions because they make you vulnerable?