i felt the same for my 20 week scan (i found out about Harry at my 20 week scan, so was worried about that) but i thought that as soon as i felt this little one move i would calm down, but like u said i was convincing myself that it wasnt baby it was gas or i was imagining that i cud feel movements!!
i am now 31 weeks and although i now have good days i still ha e days where i am scared or worried!!
i wish the feeling did go away but after what we have been through it is only natural ro worry!! hope u start to feel better and just take each day at a time! x x