Hello there,
After going through your question,I believe you have two concerns here.One is about the
back pain and
bloating and the other regarding the possibility of pregnancy.
As for the back pain after sex,it is all too common to experience that.It may b due to
1.The various positions you had sex,some positions do put alot of pressure on your lower back which may result in pain later.
2 .Weight of a heavy partner on you .
3 .Excessive arching of your back during any of the sex positions.
4 .Also the nerves supplying the vagina and the
cervix arise from the lower back so excessive thrusting or sometimes a longer penis may cause pain in the vagina or cervix which is radiated to the lower back.
So I recommend you to apply a hot water bottle over the lower back which will ease the pain or
massage the area with a local
diclofenac cream and rest for a day or two.It should subside.And next time you have sex,try using various positions instead of just one,it will b fun as well as it kind of takes the pressure off your back and ask them to be gentle .
As for the bloating after sex,it is mostly a psychological feeling and if you have sex immediately after a meal or with in an hour of having a meal,it may lead to bloated feeling as sex being a physical activity may slow down digestion for sometime.
As for your concern of pregnancy well the studies show that take action pill is efficacious till 72- 150 hrs after having unprotected sex with a failure rate i.e,
pregnancy rate of 2.9%.SO your chances of becoming pregnant a v low. You can rest assured that the risk of you becoming pregnant is very low.
Hope you got your answers.Any doubt feel free to ask.Wishing you a safe and healthy sexual life.