Brief Answer:
Pregnancy can be tested if she misses her periods.

Detailed Answer:
Hello
Welcome to HCM.
I can understand your concerns.

There is no way to judge to depth of insertion of penis during intercourse.
You are newly married. There is performance anxiety initially. Just perform intercourse as a way to attain sexual pleasure.
You will be able to do it appropriately after few attempts.
Do it with your full capacity. She will able to bear the strain once she start getting pleasure out of it.

She can become pregnant if you discharge your semen inside her vagina.
Pregnancy can be confirmed by urine pregnancy test after she misses her periods.

Hope this answers your query.
Feel free to discuss further, if you have more doubts.

Thanks.

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