my boyfriend upend wants a baby

Ok so I'm 35 years old and my boyfriend is 32. I have 5 kids from 3 previous relationships. However all my kids fathers are deceased. My new boyfriend had turned out to be the love of my life. We've discussed getting married and everything. But he doesn't have any kids and desperately wants one. I have 5 so I'm kinda done. However I would love to have a baby with him as I know he will be a great father. So we stopped using protection and now I have a feeling I might be pregnant. And now the second thoughts have started. I'm scared that I'm not ready for this and that I shouldn't have tried to get pregnant again. Even though he wants a baby because he doesn't have any, I'm starting to feel like I already have enough. And I know this is gonna sound s flush but I recently lost a whole lot of weight and got my body back to where I wanted it. I love being this weight and I don't wanna get pregnant and gain a bunch of weight again. I know how much he wants a baby, but I'm scared that if I find out I'm pregnant I might just have an abortion n tell him I lost the baby by miscarriage. I'm so confused right now. I don't know what to do. He's a really good man and I feel like I'm gonna mess everything up. Help!!!!!