Hi Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concern... Some tilt or curve in penis shape is normal & should not cause any problem in penetration. Difficulty in penetration or tight vagina is normally as result of low vaginal lubrication or vaginal dryness. This problem could arise from many reasons such as low estrogen hormone level in female, low foreplay before sex, some vaginal infection etc. Foreplay is very important part of sex. It consist of kissing , hugging, clitorial stimulation etc. It produces natural vaginal lubrication in vagina & makes it ready for sexual activity. You should try to penetrate after enough foreplay to produce enough natural lubrication. Sometimes an inexperienced male does not know right way to penetrate. In that case you could watch porn content, they could be helpful. You could also use lubricants during sex. They are easily available in market. A vaginal moisturizer used by female could also be helpful to prevent vaginal dryness for long period. Refer to a gynaecologist/ sexologist if problem persist Hope this information helps Good luck