Satya,
Your LP could be causing the problem. Clomid is the drug of choice for this - it worked for me. Just because you are on clomid doesn't mean you will conceive but it often lengthens that LP.

Karotyping is the chromosomal tests I suggested. Your partner should also be tested.
Your gp probablywon't know what you are talking about if you discuss NK cells.

I think it would be great if you could see an obstetrician. You need a thorough workover and you won't get that from a gp. IVF won't help if you have an underlying condition. So, I think it would be wise to get a consult if you can.

Wishing you lots of luck on your journey...