Losing hope

Tiffanie
Every month I I through the pregnancy mood: sleepy, hungry, sickly, irritated ect. Only to get a NOT pregnant result... I'm starting to think it's no hope and my time is up on having anymore kids. Some say I'm crazy for wanting a baby 16years after my 1St child. She's my one and only and I would like to give her a brother & sister... I've been taking prenatals but no luck is there anything pointers other then keep practicing?