Two things come to mind. Some people just have that problem: people they’re attracted to aren’t attracted to them and vice versa. It’s complicated, and I honestly can’t even begin to string together a sensible hypothetical explanation, I just know it happens for some people, myself included. The closest thing to a hypothesis I have is that the more factors are relevant (the more complicated the list of positive and negative preferences) and the rarer they are, the more the probability of a successful match decreases. This is similar to how you multiply fractions in compound probability calculations, e.g. chance of throwing 3 and 4 on two dice throws. For example there may be 6 billion people in the world, but narrow it down to one specific sex and age range, single of course, practicing Catholic, faithful Catholic, physically attractive, intellectually compatible, complementary character… if all the requirements are to be met simultaneously the pool can be in the thousands, not even millions. Say you find 1 in 10 people attractive, 1 in 5 interesting to talk to, 1 in 3 compatible in some other way… of course the traits coexist to some extent, so it’s not as bad as p = 0.1 x 0.2 x 0.33, but the numbers certainly don’t look too optimistic. The other good thing is that we have this kind of radar that we just spot the good fits and pick them out, so it’s not exactly horrible in real life, in the end, but the numbers just help visualize the challenge.
On the other hand, it’s easy to overestimate other people’s dating success rates and underestimate one’s own — the grass is always greener… Other people have their own difficulties and problems, as do their relationships.
What else? You may want to talk to a psychologist if you suspect the awkwardness could be the result of something like a difficult or distant relationship with either parent (or between parents), something traumatizing about a past boyfriend etc. That sort of stuff tends to be difficult to sort out just on one’s own. There are people in their 40s who still haven’t managed. Also introverts find it difficult (though even people with Asperger’s find partners).
Nothing wrong with that, just remember that to a lot of people it doesn’t always mean much more than a compliment or joke and says little about people’s readiness to even think about pursuing a potential relationship, even if you actually know them but especially if you don’t. There’s a reason why women sometimes have to specifically ask men to clarify their intentions and why men agonize over (alleged, or totally imaginated) hints and clues. Difficulties with self-esteem can indeed make it harder to get a good guess.
Well, looks like I’m not much off then.

It’s a great thing you can talk to your parents about all that.