@Tahli if it's implantation problems you are having rather than egg quality then I don't think putting more than one back is going to help IYKWIM? The likelihood is that they will all take and you'll have twins/triplets or none of them will and you would have lost an extra two good embryos.
Having had a very slow early blastocyst give me a BFP I always think anything that has made it to freeze has a great chance so I am a bit sentimental about blasts that don't look good on paper
Of course is it the embryo quality or implantation that's the issue? That's the million dollar question isn't it.