Thereâs no evidence that deep penetration makes any difference to your chances of conceiving, but it seems logical that some sex positions like missionary, Doggy and reverse cowgirl sex position helps in deeper penetration. Most lubricants can slow sperm movement. But hydroxyethylcellulose-based lubricant and safer in this aspect, they don't decrease sperm motility and are the most similar in consistency and viscosity to natural vaginal mucus.
Look for lubricants that contains hydroxyethylcellulose and do not contain fragrances or parabens.
Regards
Next Steps
To try intercourse positions as mentioned above.