First of all worrying about the situation is the least of your concerns, heck elope. You made a choice on what you wish to do--go through with the pregnancy. I would be very clear on what your game plan is for your future, with him included.
1-Have the baby and go to an adoption agency.
2-Have your baby and raise it with a)him involved as father b)you plan to raise the child alone.
From what you have said; it sounds as if this is something you are going to do together. I do suggest if you have been together a while and are compatible, marry. Why marriage? This protects all three of you and allows you to be a family.
You and he need to demonstrate to both family's that you are ready to be parents and a couple. This means you both discuss what exactly your plans are; how, when, and how you both plan to go on with you lives together. Now you both need to put your child first, not your parents. Through demonstrating this you will get further with your family's. The last thing they will want to hear [other than you are pregnant] is; "We don't know yet". You and your baby will need health insurance and you need to seek a job. You also need to plan how you will finish college. Many women [and the men] have gone through such. Realize, you will no longer be able to be on your parents health insurance when the baby is born & yet you cannot go uninsured. This is one reason why I suggest you do marry & it helps to decrease overall expenses for you both. I do assume you both are in love and did not want this outcome but are not devastated by it. Meanwhile, I do realize he works at Walmart, they do have good coverage for health if married. Also your state should have a CHIPS program [Child Health Insurance Programs] which are low cost if not offered free. It's based on your income level. You need to demonstrate to both sets of parents you have a plan. I say elope.
As far as telling them? First, I would get to the GYN ASAP! Be certain you have a diagnosis of pregnancy [no a urine test & being late is not enough]. Additionally, beginning prenatal care is a must, the sooner the better and you need to confirm the date of conception and the expected delivery date. I would do this first.
I would sit down with both sets of parents together. Personally, I would have both sets of your parents together and you both tell them together at the same time. No one is going to be over joyed; however, one may have common sense to the situation & they may be better controlled if everyone is in the same room together. If you and he come off with a definitive plan & are supportive of each other it will show them they are over reacting. BUT get the blood test & exam done first, now. As I said; you can elope as well. This does not mean you must reside together immediately; you need to find a place to make a home.
Only you know what you both want & what your relationship is. Always, keep in mind the baby comes first...and regardless of parental upset over the situation will not be healthy for you or the baby. I have known couples in the same situation as you; they married very young secondary to pregnancy & now are still happily married. Remember; you both have to have common life goals. How do you both plan to advance yourselves together, in careers, and raise a child. Let your family help if they are willing to help with child care. The initial shock wears off when they realize this is real & a serious matter. Yes, they will be upset but it will wear off fast. What are they going to do? Lock you both in your rooms? And yes, his parents may feel differently about you for a while. He needs to stand up for you and his child and you need to do the same. Do not allow others to rule your life.
Again, see your Gyn and confirm the pregnancy, begin your prenatal care, talk to him about life in general how you plan to proceed since he is the father, and talk to your parents when you decide how you choose to go about handling this. Have definitive answers for your parents...not "We are not sure yet". It's done, so now stand up since you will be a Mother soon.
Keep us posted, good luck, and be healthy.
Posted: 30 Sep 18:21