Ear molds - Not sealing and ways to fix it

So, we used the ear impressions now to make the shells. Unfortunately, we are again unsure about some things: My brothers shells seal the earcanal completely. He claims that it feels like pushing a finger into his ear (from an acoustic perspective). However, mine don't feel like this. They sit well and feel very comfortable but I can still hear fairly good with them inserted into my ear.

I've read that it has to seal 100% in order to reproduce all the bass frequencies correctly. Is there a way to fix this problem or do I have to make new ear impressions? I'm afraid that this will not solve the problem, because the impressions really look fairly good to me and apparently also to you guys (see my previous post "Ear Impressions")

I've also read that you can apply some additional acrylic layers to the stem to improve the seal.

What would you guys suggest to do?

Some pictures:

Impressions(mine left, my brothers right): http://i.imgur.com/JSdABjW.jpg

My earmolds (all perspectives): http://imgur.com/a/7HLg7

Thanks in advance