Does anyone else get this weird feeling?

I don’t know why but for some reason I don’t worry before meeting people but after I’ve met them. I think about whether what I said or did was ‘normal.’ I feel like I’m too nice, I try to to make others happy and then I’m left feeling down because I feel like I wasn’t strong or confident or that I may have come off as flirtatious (esp towards opp gender). I smile a lot and my voice goes high pitched (I don’t feel that way it just comes off like this). I get uncomfortable meeting them because I’m not sure what they think of me. I get caught up thinking about this and then am anxious about meeting them again because I don’t want to. 

What do I have to do to seem confident &amp; normal? Where’s the boundary of being polite to over the top flirty/ nice? 

I think this is why I hate social interactions so much :(