Fed up!

So my husband and I have been ttc for 4yrs now and no luck. My patience is running thin and I am so ready to stop and give up. I don't know what we are doing wrong. I temp everyday, use Clearblue Advance Digital ovulation tests and have sex when its the right time. I also bought and started taking these pills called fertileprep which is tmi supposed to help make youre cervical mucous to be more friendlier to sperm. Was really hoping and praying we definitely got it this time and Aunt Flo showed up. Anytime I tried to talk with doctor's either regular or ob, they keep telling me need to do fertility, but I don't have the money for that nor the mental ability to go through that. Can anyone shed some light on what might be wrong or what we should do or try?! Please and Thank You.