I feel bad for even feeling this way

I’ve been trying to conceive since the beginning of this yr in Jan with no success at all and it’s draining and depressing. I feel bad for feeling this way because i know some woman can’t even have kids and I already have 2 beautiful children ages 9 and 7. I just don’t understand why it’s taking me so long to get pregnant I had no problem with my other 2. Then again I was in my 20s and I’m now 30. I just want one more baby!